{"id":1249,"date":"2013-10-10T19:43:32","date_gmt":"2013-10-10T19:43:32","guid":{"rendered":"http:\/\/jacobimed.org\/NS\/?page_id=1249"},"modified":"2013-10-10T19:43:32","modified_gmt":"2013-10-10T19:43:32","slug":"recommendations-and-rationale","status":"publish","type":"page","link":"https:\/\/jacobimed.org\/old\/ambulatory\/mlove\/curriculumprevention\/diabetes-screening\/recommendations-and-rationale\/","title":{"rendered":"Recommendations and Rationale"},"content":{"rendered":"<p>&nbsp;<\/p>\n<h2>Recommendations and Rationale<\/h2>\n<h1>Screening for Type 2 Diabetes Mellitus in Adults<\/h1>\n<h3>U.S. Preventive Services Task Force (USPSTF)<\/h3>\n<hr \/>\n<p class=\"size2\">This statement summarizes the current U.S. Preventive Services<br \/>\nTask Force (USPSTF) recommendation on screening for type 2 diabetes mellitus in<br \/>\nadults, and updates the 1996 recommendation contained in the <em>Guide to<br \/>\nClinical Preventive Services<\/em>, Second Edition<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref1\">1<\/a><\/sup>.<\/p>\n<hr \/>\n<p><a name=\"summary\"><\/a><\/p>\n<table id=\"table1\" style=\"width: 100%;\" border=\"0\" bgcolor=\"#ffffcc\">\n<tbody>\n<tr>\n<td valign=\"top\">\n<h4>Summary of Recommendation<\/h4>\n<ul>\n<li><strong>The USPSTF concludes that the evidence is insufficient<br \/>\n\t\t\tto recommend for or against routinely screening asymptomatic adults<br \/>\n\t\t\tfor type 2 diabetes, impaired glucose tolerance, or impaired fasting<br \/>\n\t\t\tglucose.<\/strong>&nbsp;<\/p>\n<p><strong>Rating:<br \/>\n\t\t\t<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/ratings.htm#irec\">I<br \/>\n\t\t\tRecommendation<\/a>.<\/strong><\/p>\n<p><em>Rationale: <\/em>The USPSTF found good evidence that available<br \/>\n\t\t\tscreening tests can accurately detect type 2 diabetes during an<br \/>\n\t\t\tearly, asymptomatic phase. The USPSTF also found good evidence that<br \/>\n\t\t\tintensive glycemic control in patients with clinically detected (not<br \/>\n\t\t\tscreening detected) diabetes can reduce the progression of<br \/>\n\t\t\tmicrovascular disease. However, the benefits of tight glycemic<br \/>\n\t\t\tcontrol on microvascular clinical outcomes take years to become<br \/>\n\t\t\tapparent. It has not been demonstrated that beginning diabetes<br \/>\n\t\t\tcontrol early as a result of screening provides an incremental<br \/>\n\t\t\tbenefit compared with initiating treatment after clinical diagnosis.<br \/>\n\t\t\tExisting studies have not shown that tight glycemic control<br \/>\n\t\t\tsignificantly reduces macrovascular complications including<br \/>\n\t\t\tmyocardial infarction and stroke. The USPSTF found poor evidence to<br \/>\n\t\t\tassess possible harms of screening. As a result, the USPSTF could<br \/>\n\t\t\tnot determine the balance of benefits and harms of routine screening<br \/>\n\t\t\tfor type 2 diabetes.\n\t\t\t<\/p>\n<\/li>\n<li><strong>The USPSTF recommends screening for type 2 diabetes in<br \/>\n\t\t\tadults with hypertension or hyperlipidemia.<\/strong>&nbsp;<\/p>\n<p><strong><br \/>\n\t\t\tRating:<br \/>\n\t\t\t<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/ratings.htm#brec\">B<br \/>\n\t\t\tRecommendation<\/a>.<\/strong><\/p>\n<p><em>Rationale: <\/em>The USPSTF found good evidence that, in<br \/>\n\t\t\tadults who have hypertension and clinically detected diabetes,<br \/>\n\t\t\tlowering blood pressure below conventional target blood pressure<br \/>\n\t\t\tvalues reduces the incidence of cardiovascular events and<br \/>\n\t\t\tcardiovascular mortality; this evidence is considered fair when<br \/>\n\t\t\textrapolated to cases of diabetes detected by screening. Among<br \/>\n\t\t\tpatients with hyperlipidemia, there is good evidence that detecting<br \/>\n\t\t\tdiabetes substantially improves estimates of individual risk for<br \/>\n\t\t\tcoronary heart disease, which is an integral part of decisions about<br \/>\n\t\t\tlipid-lowering therapy.\n\t\t<\/p>\n<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p><a name=\"contents\"><\/a><\/p>\n<h2>Contents<\/h2>\n<p>\n<a href=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/recommendations_and_rationale.htm#clinical\"><img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Clinical<br \/>\nConsiderations<\/a><br \/>\n<a href=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/recommendations_and_rationale.htm#scientific\"><img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Scientific<br \/>\nEvidence<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#recommendations\"><br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Recommendations of Others<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#references\"><br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> References<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#members\"><br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Members of the Task Force<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#contact\"><br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Contact the Task Force<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#available\"><br \/>\n<img loading=\"lazy\" decoding=\"async\" src=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/arrow_rt.gif\" border=\"0\" alt=\" \" width=\"8\" height=\"11\" \/> Available Products<\/a><\/p>\n<p>&nbsp;<\/p>\n<table id=\"table2\" border=\"0\">\n<tbody>\n<tr valign=\"top\" bgcolor=\"#ffffcc\">\n<td><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/ratings.htm\"><br \/>\n\t\t<span style=\"color: #990099; font-size: x-small;\"><strong>Task Force Ratings<\/strong><\/span><\/a><br \/>\n\t\t<span style=\"color: #990099; font-size: xx-small;\">Strength of Recommendations and Quality<br \/>\n\t\tof Evidence<\/span>\n\t\t<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<p><a name=\"clinical\"><\/a><\/p>\n<h2>Clinical Considerations<\/h2>\n<ul>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a><\/p>\n<li>In the absence of evidence of direct benefits of routine screening for<br \/>\n\ttype 2 diabetes, the decision to screen individual patients is a matter of<br \/>\n\tclinical judgment. Patients at increased risk for cardiovascular disease may<br \/>\n\tbenefit most from screening for type 2 diabetes, since management of<br \/>\n\tcardiovascular risk factors leads to reductions in major cardiovascular<br \/>\n\tevents. Clinicians should assist patients in making that choice. In<br \/>\n\taddition, clinicians should be alert to symptoms suggestive of diabetes<br \/>\n\t(i.e., polydipsia and polyuria) and test anyone with these symptoms.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>Screening for diabetes in patients with hypertension or hyperlipidemia<br \/>\n\tshould be part of an integrated approach to reduce cardiovascular risk.<br \/>\n\tLower targets for blood pressure (i.e., diastolic blood pressure <span style=\"text-decoration: underline;\">&lt;<\/span>80<br \/>\n\tmm Hg) are beneficial for patients with diabetes and high blood pressure.<br \/>\n\tThe report of the Adult Treatment Panel III of the National Cholesterol<br \/>\n\tEducation Program recommends lower targets for low-density lipoprotein<br \/>\n\tcholesterol for patients with diabetes. Attention to other risk factors such<br \/>\n\tas physical inactivity, diet, and overweight, is also important, both to<br \/>\n\tdecrease risk for heart disease and to improve glucose control.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>Three tests have been used to screen for diabetes: fasting plasma<br \/>\n\tglucose (FPG), 2-hour post-load plasma glucose (2-hour PG), and hemoglobin<br \/>\n\tA1c (HbA1c). The American Diabetes Association (ADA) has recommended the FPG<br \/>\n\ttest (<span style=\"text-decoration: underline;\">&gt;<\/span>126 mg\/dL) for screening because it is easier and faster to<br \/>\n\tperform, more convenient and acceptable to patients, and less expensive than<br \/>\n\tother screening tests. The FPG test is more reproducible than the 2-hour PG<br \/>\n\ttest, has less intraindividual variation, and has similar predictive value<br \/>\n\tfor development of microvascular complications of diabetes. Compared with<br \/>\n\tthe FPG test, the 2-hour PG test may lead to more individuals being<br \/>\n\tdiagnosed as diabetic. HbA1c is more closely related to FPG than to 2-hour<br \/>\n\tPG, but at the usual cut-points it is less sensitive in detecting lower<br \/>\n\tlevels of hyperglycemia. The random capillary blood glucose (CBG) test has<br \/>\n\tbeen shown to have reasonable sensitivity (75 percent at a cut-point of <span style=\"text-decoration: underline;\">&gt;<\/span>120<br \/>\n\tmg\/dL) in detecting persons who have either an FPG level <span style=\"text-decoration: underline;\">&gt;<\/span>126 mg\/dL<br \/>\n\tor a 2-hour PG level <span style=\"text-decoration: underline;\">&gt;<\/span>200 mg\/dL, if results are interpreted according<br \/>\n\tto age and time since last meal; however, the random blood glucose test is<br \/>\n\tless well standardized for screening for diabetes.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>The ADA recommends confirmation of a diagnosis of diabetes with a<br \/>\n\trepeated FPG test on a separate day, especially for patients with borderline<br \/>\n\tFPG results and patients with normal FPG levels for whom suspicion of<br \/>\n\tdiabetes is high. The optimal screening interval is not known. The ADA, on<br \/>\n\tthe basis of expert opinion, recommends an interval of every three years but<br \/>\n\tshorter intervals in high-risk persons.<\/p>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>Regardless of whether the clinician and patient decide to screen for<br \/>\n\tdiabetes, patients should be encouraged to exercise, eat a healthy diet, and<br \/>\n\tmaintain a healthy weight, choices that may prevent or forestall the<br \/>\n\tdevelopment of type 2 diabetes. More aggressive interventions to establish<br \/>\n\tand maintain these behaviors should be considered for patients at increased<br \/>\n\trisk for developing diabetes, such as those who are overweight, have a<br \/>\n\tfamily history of diabetes, or have a racial or ethnic background associated<br \/>\n\twith an increased risk (e.g., American Indians). Intensive programs of<br \/>\n\tlifestyle modification (diet, exercise, and behavior) should also be<br \/>\n\tconsidered for patients who have impaired fasting glucose or impaired<br \/>\n\tglucose tolerance, since several large trials have demonstrated that these<br \/>\n\tprograms can significantly reduce the incidence of diabetes in these<br \/>\n\tpatients. Evidence and recommendations regarding counseling about diet,<br \/>\n\tphysical activity, and obesity are provided in the USPSTF evidence summaries<br \/>\n\t&#8220;<a href=\"http:\/\/www.ahcpr.gov\/clinic\/uspstf\/uspsdiet.htm\">Counseling to<br \/>\n\tPromote a Healthy Diet<\/a>,&#8221; &#8220;<a href=\"http:\/\/www.ahcpr.gov\/clinic\/uspstf\/uspsphys.htm\">Counseling<br \/>\n\tto Promote Physical Activity<\/a>,&#8221; and &#8220;<a href=\"http:\/\/www.ahcpr.gov\/clinic\/uspstf\/uspsobes.htm\">Screening<br \/>\n\tand Treatment for Obesity in Adults<\/a>,&#8221; available on the Agency for<br \/>\n\tHealthcare Research and Quality Web site at<br \/>\n\t<a href=\"http:\/\/www.preventiveservices.ahrq.gov\/\"><br \/>\n\thttp:\/\/www.preventiveservices.ahrq.gov<\/a>.\n\t<\/li>\n<\/ul>\n<p class=\"size2\"><a href=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/recommendations_and_rationale.htm#contents\">Return to Contents<\/a><\/p>\n<p>\n<a name=\"scientific\"><\/a><\/p>\n<h2>Scientific Evidence<\/h2>\n<h3>Epidemiology and Clinical Consequences<\/h3>\n<p>The burden of suffering caused by type 2 diabetes is enormous. Among<br \/>\nindividuals aged 40-74, the prevalence increased from 8.9 percent for the period<br \/>\n1976-80, to 12.3 percent for the period 1988-94.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref4\">4<\/a><\/sup><br \/>\nCurrent prevalence in the United States is likely even higher due to the<br \/>\nincreasing prevalence of obesity.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref5\">5<\/a><\/sup><br \/>\nPatients with type 2 diabetes are at increased risk for both microvascular and<br \/>\nmacrovascular disease. Microvascular disease contributes to high rates of<br \/>\nblindness, end stage renal disease, and lower extremity amputations.<br \/>\nMacrovascular disease accounts for a 2 to 4-fold increased risk for heart<br \/>\ndisease and stroke. In addition, a substantial number of people who have<br \/>\nelevations in blood glucose not meeting criteria for diabetes (impaired fasting<br \/>\nglucose or impaired glucose tolerance) are at increased risk for progression to<br \/>\ndiabetes and for cardiovascular disease.<\/p>\n<p>The 10-year incidence of blindness among those with type 2 diabetes of 20-25<br \/>\nyears&#8217; duration is between 5 and 15 percent, and the 10-year incidence of visual<br \/>\ndeterioration (doubling of the visual angle) is between 35 and 45 percent, with<br \/>\nthe higher rates for those requiring insulin.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref6\">6<\/a><\/sup><br \/>\nThe highest risk is among those who have a longer time to develop visual<br \/>\ncomplications because of onset of diabetes at a younger age.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref7\">7-8<\/a><\/sup><\/p>\n<p>Some patients with diabetes manifest diabetic nephropathy, a condition that<br \/>\ncan progress to chronic renal failure (CRF). The incidence of CRF among those<br \/>\nwithout macroalbuminuria at diagnosis of type 2 diabetes is about 0.5 percent<br \/>\nafter 15 years of diabetes duration and 10 percent after 30 years. The incidence<br \/>\nof CRF is substantially higher (about 12 percent after 15 years) among those<br \/>\nwith macroalbuminuria at time of diagnosis of diabetes.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref9\">9<\/a><\/sup><\/p>\n<p>Two cohort studies found that the 20-25-year cumulative incidence of lower<br \/>\nextremity amputation (LEA) in patients with type 2 diabetes is between 3 and 11<br \/>\npercent.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref10\">10-11<\/a><\/sup><br \/>\nIn the United Kingdom Prospective Diabetes Study (UKPDS) cohort, between 1 and 2<br \/>\npercent of participants had had an amputation within 10 years<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a><\/sup>.<br \/>\nIn the Wisconsin Epidemiologic Study of Diabetic Retinopathy population-based<br \/>\ncohort, about 7 percent of those with type 2 diabetes of short duration had had<br \/>\nan amputation within 14 years.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref13\">13<\/a><\/sup><\/p>\n<p>Elevated blood glucose is an independent risk factor for cardiovascular<br \/>\ndisease (CVD). The risk increases with the level of glucose. The absolute<br \/>\nprevalence of established CVD at diagnosis of type 2 diabetes ranges from 8 to<br \/>\n23 percent (depending on the presence of other CVD risk factors) and at least 14<br \/>\nprospective cohort studies have found that the risk for CVD events in diabetic<br \/>\nmen is about twice that in nondiabetics, even after adjusting for age,<br \/>\nhypertension, dyslipidemia, and smoking.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref3\">3<\/a><\/sup><br \/>\nFor women, the adjusted CVD risk among diabetics is elevated as much as fourfold<br \/>\ncompared with nondiabetics. In the UKPDS cohort of diabetic patients undergoing<br \/>\nconventional treatment, there were 17 events of myocardial infarction (MI), 5<br \/>\nevents of stroke, and 12 events of diabetes-related deaths, respectively, per<br \/>\n1,000 patient-years.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a><\/sup><\/p>\n<p>Diabetes also imposes a significant economic burden. In 1997, the U.S. health<br \/>\ncare system spent some $98 billion on medical care and lost productivity for<br \/>\npeople with type 2 diabetes.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref14\">14<\/a><\/sup><br \/>\nMany individuals who satisfy the criteria for type 2 diabetes have not been<br \/>\ndiagnosed. Data from the third National Health and Nutrition Examination Survey<br \/>\n(NHANES III) showed that 3 percent of the adult population aged 20 and older had<br \/>\nnot been diagnosed and yet met the diagnostic criteria for diabetes.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref4\">4<\/a><\/sup><\/p>\n<h3>Accuracy and Reliability of Screening Tests<\/h3>\n<p>Determining the accuracy of screening tests for type 2 diabetes is<br \/>\ncomplicated by uncertainty of what is the most appropriate gold standard for<br \/>\ncomparison. Definitions of diabetes were originally developed using results of<br \/>\n2-hour PG to identify a population at substantially increased risk for<br \/>\nretinopathy. The criterion for an abnormal FPG level was developed based on<br \/>\n2-hour PG, and recently revised downward (from 140 mg\/dL to 126 mg\/dL) to make<br \/>\nthe sensitivity of FPG comparable with that of 2-hour PG. Additional<br \/>\ncriteria&mdash;impaired fasting glucose (110-125 mg\/dL) and impaired glucose tolerance<br \/>\n(140-199 mg\/dL for 2-hour PG)&mdash;have been developed to define persons who have<br \/>\nless severe elevations of blood glucose. A study using NHANES III data<br \/>\ndemonstrated that, compared with FPG, the 2-hour PG as a screening test leads to<br \/>\nmore individuals being diagnosed as diabetic.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref4\">4<\/a><\/sup><\/p>\n<p>Large population-based studies have examined the sensitivity of 2-hour PG,<br \/>\nFPG, and HbA1c for identifying patients with retinopathy. Sensitivity and<br \/>\nspecificity for detecting retinopathy were in the range of 75-80 percent for all<br \/>\nthree tests using the following thresholds: FPG <span style=\"text-decoration: underline;\">&gt;<\/span>126 mg\/dL, 2-hour PG <span style=\"text-decoration: underline;\"><br \/>\n&gt;<\/span> 200 mg\/dL, or HbA1c <span style=\"text-decoration: underline;\">&gt;<\/span>6.4 percent.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref15\">15-17<\/a><\/sup><br \/>\nOther studies have examined whether these tests predict future cardiovascular<br \/>\ndisease (CVD) events. A recent meta-regression analysis of 20 observational<br \/>\nstudies found that both FPG and 2-hour PG were significantly associated with<br \/>\nfuture CVD events in a continuous graded fashion, beginning at levels consistent<br \/>\nwith impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) and<br \/>\nincreasing more steeply at the highest glucose levels.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref18\">18<\/a><\/sup><br \/>\nAmong those with previously undiagnosed type 2 diabetes who are in the low range<br \/>\nof &#8220;diabetic level&#8221; FPG (i.e., FPG between 126 and 140 mg\/dL), HbA1c was normal<br \/>\nin about 60 percent of those tested, indicating it may be less sensitive for<br \/>\ndetecting lower levels of hyperglycemia.<\/p>\n<p>In clinical practice, the requirement for a screening test to be fasting (as<br \/>\nwith the FPG) or post-glucose load (as with 2-hour PG) presents logistical<br \/>\nproblems. A well-conducted, population-based study found that random CBG had<br \/>\nsensitivity and specificity in the 75-80 percent range for detecting type 2<br \/>\ndiabetes defined by older criteria (i.e., FPG <span style=\"text-decoration: underline;\">&gt;<\/span> 140 mg\/dL or 2-hour PG<br \/>\ngreater than or equal to 200 mg\/dL), but only if results were interpreted<br \/>\naccording to age and time since last meal.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref19\">19<\/a><\/sup><\/p>\n<h3>Effectiveness of Early Treatment<\/h3>\n<p>No trial has been conducted to establish whether systematic screening for<br \/>\ndiabetes improves health outcomes compared with usual care. Establishing the<br \/>\nhealth benefits of screening for type 2 diabetes is complex because under<br \/>\ncurrent practice many patients with diabetes are detected through haphazard<br \/>\nscreening: about 50 percent of adults over 45 may have been screened for<br \/>\ndiabetes in a 3-year period.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref20\">20<\/a><\/sup><\/p>\n<p>The USPSTF attempted to compare the expected health outcomes from a strategy<br \/>\nof systematic screening to those from existing care. In the absence of direct<br \/>\nevidence from a trial of screening, the USPSTF examined indirect evidence to<br \/>\nestimate whether screening, early diagnosis, and treatment of type 2 diabetes<br \/>\nwere likely to improve four health outcomes compared with usual care\/clinical<br \/>\ndetection:<\/p>\n<ul>\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a><\/p>\n<li>Visual impairment.\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>Chronic renal failure.\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>Lower extremity amputations.\n<p>&nbsp;<\/p>\n<p class=\"size2\"><a name=\"ref2\"><\/a>\n\t<\/p>\n<\/li>\n<li>CVD events. <\/li>\n<\/ul>\n<p>Additionally, the results from recent RCTs demonstrate the effectiveness of<br \/>\nintensive lifestyle interventions in reducing the incidence of diabetes in<br \/>\nindividuals with impaired fasting glucose or impaired glucose tolerance. Three<br \/>\nlarge trials in the United States, Finland, and China have demonstrated that<br \/>\nintensive programs of lifestyle modification (diet, exercise, and behavior<br \/>\nmodification) can reduce incidence of diabetes by up to 58 percent in these<br \/>\npatients.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref21\">21-23<\/a><\/sup><\/p>\n<h4>Visual Impairment<\/h4>\n<p>Although early retinopathy is present in a substantial portion of patients<br \/>\nwith diabetes at the time of initial diagnosis, severe retinopathy (i.e., that<br \/>\nrequiring treatment) and visual problems usually develop later in the course of<br \/>\ndisease. Two well-performed RCTs have shown that tight glycemic control reduces<br \/>\nthe relative risk for development or progression of retinopathy by 29-40<br \/>\npercent.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12-24<\/a><\/sup><br \/>\nAfter 10 years of followup in the UKPDS, 7.6 percent of those in the tight<br \/>\ncontrol group required laser photocoagulation compared with 10.3 percent of<br \/>\npatients in the conventional treatment arm; however, no difference in visual<br \/>\noutcomes was detected.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref25\">25<\/a>,<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref26\">26<\/a><\/sup><br \/>\nOne large well-performed RCT found that tighter control of systolic blood<br \/>\npressure (improvement of approximately 10 mm Hg) among hypertensive diabetics<br \/>\ndecreased the need for retinal photocoagulation by an absolute 4.1 percent and<br \/>\nreduced deterioration in visual acuity by an absolute 9.2 percent over 7.5<br \/>\nyears.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref27\">27<\/a><\/sup><br \/>\nThe incidence of blindness, however, was similar in both groups (3.3 percent vs.<br \/>\n2.4 percent) in this study.<\/p>\n<p>The USPSTF concluded that, although retinal photocoagulation is effective in<br \/>\nreducing the incidence of visual impairment among those with severe retinopathy<br \/>\nor macular edema, most patients detected by routine screening will not require<br \/>\nthis intervention. Further, although tight glycemic control reduces the<br \/>\ndevelopment and progression of retinopathy, its effects on serious visual<br \/>\nimpairment are less clear and probably occur 10 years or more after the<br \/>\ndiagnosis of diabetes. The degree to which tight glycemic control during the<br \/>\npreclinical period between screening and clinical detection (when glucose levels<br \/>\nare lower compared with later stages of the disease) reduces retinopathy and<br \/>\nlater visual impairment is even less certain.<\/p>\n<h4>Chronic Renal Failure<\/h4>\n<p>Three treatments have been examined to reduce the incidence of CRF among<br \/>\ndiabetics: tight glycemic control, tight blood pressure control, and medications<br \/>\nthat interrupt the angiotensin-renin system (angiotensin converting enzyme [ACE]<br \/>\ninhibitors and angiotensin receptor blockers [ARBs]).<\/p>\n<p>Evidence from several RCTs shows that tight glycemic control, and tight blood<br \/>\npressure control, reduce the development and progression of albuminuria in those<br \/>\nwith type 2 diabetes, but neither intervention had a statistically significant<br \/>\neffect on the incidence of CRF.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a>,<a>24<\/a>,<a>27<\/a><\/sup><br \/>\nGood evidence shows that ACE inhibitors or ARBs, or both, reduce the development<br \/>\nand progression of albuminuria and CRF among those with type 2 diabetes.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref28\">28-37<\/a><\/sup><br \/>\nTwo of these studies, both involving diabetics with macroalbuminuria, found a<br \/>\nreduction in CRF in patients taking ARBs compared with placebo.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref32\">32<\/a>,<a>33<\/a><\/sup><br \/>\nEvidence is mixed as to whether ACE inhibitors are more effective than<br \/>\nbeta-blockers in reducing development and progression of albuminuria.<\/p>\n<p>Between 3 and 8 percent of individuals with diabetes (detected clinically or<br \/>\nby screening) have macroalbuminuria. As a result, most patients detected by<br \/>\nscreening will be at low risk (&lt;1 percent) for developing CRF over the next 15<br \/>\nyears.<\/p>\n<p>The USPSTF concluded that, although tight glycemic and blood pressure control<br \/>\nand use of ACE inhibitors and ARBs reduce the development and progression of<br \/>\nalbuminuria, it could not determine whether initiating these treatments earlier<br \/>\nas a result of screening would have an important impact on CRF.<\/p>\n<h4>Lower Extremity Amputations<\/h4>\n<p>Three types of treatment have been tested to reduce LEA: tight glycemic<br \/>\ncontrol, tight blood pressure control, and foot care programs. The UKPDS<br \/>\nreported a trend toward a lower incidence of amputations with both tight<br \/>\nglycemic control<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a><\/sup><br \/>\nand tight blood pressure control<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref27\">27<\/a><\/sup>,<br \/>\nbut the differences did not attain statistical significance. A recent<br \/>\nwell-conducted systematic review examined the efficacy of foot care programs on<br \/>\nthe incidence of foot ulcers and amputations, and its findings were<br \/>\ninconclusive.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref38\">38<\/a><\/sup><br \/>\nWell-conducted trials of diabetics at high risk for foot ulcers found that<br \/>\nintensive programs including patient education, special shoes, and health care<br \/>\ninterventions can reduce the incidence of both foot ulcers and LEAs by as much<br \/>\nas 60 percent.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref39\">39<\/a>,<a>40<\/a><\/sup><\/p>\n<p>The USPSTF concluded that LEA in diabetics occurs primarily as a late<br \/>\ncomplication related to the development of distal sensory neuropathy and<br \/>\nperipheral vascular disease, both of which take time to develop. Although foot<br \/>\ncare programs, and perhaps tight glycemic and blood pressure control, may reduce<br \/>\nLEA over the long term, the Task Force found no evidence that early<br \/>\nimplementation of these interventions during the time between screening and<br \/>\nclinical detection would have an impact on the later development of LEA.<\/p>\n<h4>Cardiovascular Disease<\/h4>\n<p>Four treatments to reduce the incidence of CVD events among patients with<br \/>\ndiabetes have been studied in high-quality RCTs: tight glycemic control, tight<br \/>\nblood pressure control, treatment of dyslipidemia, and aspirin. No RCT has<br \/>\ndemonstrated a statistically significant reduction in total CVD events from<br \/>\ntight glycemic control. The UKPDS trial (after 10 years of followup) showed a<br \/>\ntrend toward reduced CVD events in patients randomized to tight glycemic<br \/>\ncontrol.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a><\/sup><br \/>\nThese patients had lower rates of myocardial infarction (14.7 vs. 17.4 events<br \/>\nper 1,000 patient-years) and sudden death (0.9 vs. 1.6 events per 1,000<br \/>\npatient-years) than those receiving conventional management. Further, there were<br \/>\nno reductions in stroke (Relative Risk [RR], 1.11), heart failure (RR, 0.91),<br \/>\nangina (RR, 1.02), or all-cause mortality (RR, 0.94). <\/p>\n<p>A number of recent RCTs have examined various aspects of the treatment of<br \/>\nhypertension among patients with type 2 diabetes. Principal findings are that an<br \/>\naggressive approach to blood pressure control among patients with diabetes<br \/>\nreduces CVD events by a relative 50 percent<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref27\">27<\/a>,<a>41<\/a><\/sup>;<br \/>\ntreatment of isolated systolic hypertension among older patients with diabetes<br \/>\nreduces CVD events by a relative 34-69 percent<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref42\">42<\/a>,<a>43<\/a><\/sup>;<br \/>\ntreatment of those with diabetes and at least one other CVD risk factor with<br \/>\nramipril (regardless of whether they have hypertension) reduces CVD events by a<br \/>\nrelative 22 percent and all-cause mortality by a relative 16 percent<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref37\">37<\/a><\/sup>;<br \/>\nand ACE inhibitors and ARBs are useful antihypertensive agents for diabetics.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref41\">41<\/a>,<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref44\">44<\/a><\/sup><\/p>\n<p>Several secondary prevention trials of treatments for patients with lipid<br \/>\nabnormalities had enough patients with diabetes to permit subgroup analyses.<br \/>\nLipid treatment reduced the incidence of coronary heart disease (CHD) events by<br \/>\nabout the same relative percentage among those with diabetes as among those<br \/>\nwithout diabetes (relative risk reduction between 19 and 42 percent).<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref45\">45-47<\/a><\/sup><br \/>\nNo primary prevention trial of lipid therapy has included sufficient numbers of<br \/>\npatients with diabetes to perform reliable analyses, although trends in these<br \/>\ntrials are also in the direction of benefit. The Heart Protection Study (HPS)<br \/>\nfound that including simvastatin in the treatment regimen of diabetic patients<br \/>\nreduces major vascular events (myocardial infarction, stroke, and<br \/>\nrevascularization) from 25 percent to 20 percent, i.e., prevents one major<br \/>\nvascular event in 20 patients, over a 5-year period.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref48\">48<\/a><\/sup><br \/>\nAspirin reduces CHD in both diabetics and nondiabetics, with a comparable<br \/>\nrelative risk reduction (about 30 percent) in both groups.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref49\">49-51<\/a><\/sup><\/p>\n<h3>Potential Harms of Screening and Treatment<\/h3>\n<p>Screening for type 2 diabetes could cause harm in several ways. A diagnosis<br \/>\nof diabetes could potentially cause &#8220;labeling&#8221; in asymptomatic individuals<br \/>\n(i.e., anxiety or a negative change in self-perception, or both) and could lead<br \/>\nto social consequences (e.g., loss of insurability). However, there is little<br \/>\nevidence that patients found to have diabetes at screening experience any<br \/>\nadverse effect of labeling.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref52\">52<\/a><\/sup><br \/>\nEarly detection could subject individuals to the potential risks of treatment<br \/>\nfor longer than if the diagnosis was made clinically, with uncertain benefits.<br \/>\nFinally, screening could produce false-positive results, especially since there<br \/>\nis not yet complete consensus on criteria for diagnosing diabetes in<br \/>\nasymptomatic persons. Further complicating the issue are natural history data<br \/>\nthat show that between 30 and 50 percent of persons labeled as having impaired<br \/>\nglucose tolerance or impaired fasting glucose will revert to normal glycemia<br \/>\nwithout developing type 2 diabetes.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref53\">53-59<\/a><\/sup><br \/>\nFalse-positive screening tests could contribute to psychological distress, a<br \/>\nproblem known to exist for other conditions.<\/p>\n<p>Treatments for diabetes are relatively safe. Tight glycemic control at a time<br \/>\nwhen glycemic levels are relatively low (i.e., the time between screening and<br \/>\nclinical diagnosis) can induce hypoglycemia. In the UKPDS, 2.3 percent of people<br \/>\non insulin suffered a major hypoglycemic episode each year, as did 0.4-0.6<br \/>\npercent of those on oral hypoglycemic agents.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a><\/sup><br \/>\nACE inhibitors<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref60\">60<\/a><\/sup><br \/>\nand statins<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref61\">61,62<\/a><\/sup><br \/>\nhave reasonably low levels of serious adverse effects. Finally, although the<br \/>\nimpact of diabetes treatment on quality of life has been a concern, data from<br \/>\nRCTs indicate that better glycemic control among symptomatic patients improves<br \/>\nquality of life, although these findings may not apply to patients detected by<br \/>\nscreening during the preclinical phase.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref12\">12<\/a>,<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref63\">63-65<\/a><\/sup><\/p>\n<p>The USPSTF concluded that, despite the potential for harm in patients whose<br \/>\ndiabetes is detected by screening, the magnitude of the problem is unknown. The<br \/>\npotential harm for patients is an important consideration because, even if early<br \/>\ndetection is assumed to be beneficial, several thousand people in the general<br \/>\npopulation may need to be screened to prevent a single diabetes-related<br \/>\ncomplication over a 5-year period.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref3\">3<\/a><\/sup><br \/>\nWhen screening is targeted to patients with hypertension or hyperlipidemia,<br \/>\nhowever, the number needed to screen to prevent a cardiovascular event is<br \/>\nsubstantially lower.<sup><a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm#ref3\">3<\/a><\/sup><\/p>\n<p class=\"size2\"><a href=\"file:\/\/\/C:\/Documents%20and%20Settings\/LauraKoo\/Desktop\/ambulatory_backup\/mlove\/CurriculumPrevention\/Diabetes%20Screening\/recommendations_and_rationale.htm#contents\">Return to Contents<\/a><br \/>\n<a href=\"http:\/\/www.ahcpr.gov\/clinic\/3rduspstf\/diabscr\/diabetrr2.htm\">Proceed to<br \/>\nNext Section<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; Recommendations and Rationale Screening for Type 2 Diabetes Mellitus in Adults U.S. Preventive Services Task Force (USPSTF) This statement summarizes the current U.S. Preventive Services Task Force (USPSTF) recommendation on screening for type 2 diabetes mellitus in adults, and updates the 1996 recommendation contained in the Guide to Clinical Preventive Services, Second Edition1. Summary&#8230;.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1247,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"class_list":["post-1249","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/pages\/1249","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/comments?post=1249"}],"version-history":[{"count":1,"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/pages\/1249\/revisions"}],"predecessor-version":[{"id":1250,"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/pages\/1249\/revisions\/1250"}],"up":[{"embeddable":true,"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/pages\/1247"}],"wp:attachment":[{"href":"https:\/\/jacobimed.org\/old\/wp-json\/wp\/v2\/media?parent=1249"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}