Diabetes mellitus type 2 screening


 * Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [mailto:psingh@perfuse.org];

Screening and prevention
Interest has arisen in preventing diabetes due to research on the benefits of treating patients before overt diabetes. Although the U.S. Preventive Services Task Force (USPSTF) concluded that "the evidence is insufficient to recommend for or against routinely screening asymptomatic adults for type 2 diabetes, impaired glucose tolerance, or impaired fasting glucose", this was a grade I recommendation when published in 2003. However, the USPSTF does recommend screening for diabetics in adults with hypertension or hyperlipidemia (grade B recommendation).

In 2005, an evidence report by the Agency for Healthcare Research and Quality concluded that "there is evidence that combined diet and exercise, as well as drug therapy (metformin, acarbose), may be effective at preventing progression to DM in IGT subjects".

Accuracy of tests for early detection
If a 2-hour postload glucose level of at least 11.1 mmol/L (≥ 200 mg/dL) is used as the reference standard, the fasting plasma glucose > 7.0 mmol/L (126 mg/dL) diagnoses current diabetes with :
 * sensitivity about 50%
 * specificity greater than 95%

A random capillary blood glucose > 6.7 mmol/L (120 mg/dL) diagnoses current diabetes with :
 * sensitivity = 75%
 * specificity = 88%

Glycosylated hemoglobin values that are elevated (over 5%), but not in the diabetic range (not over 7.0%) are predictive of subsequent clinical diabetes in US female health professionals. In this study, 177 of 1061 patients with glycosylated hemoglobin value less than 6% became diabetic within 5 years compared to 282 of 26281 patients with a glycosylated hemoglobin value of 6.0% or more. This equates to a glycosylated hemoglobin value of 6.0% or more having:
 * sensitivity = 16.7%
 * specificity = 98.9%

Benefit of early detection
Since publication of the USPSTF statement, a randomized controlled trial of prescribing acarbose to patients with "high-risk population of men and women between the ages of 40 and 70 years with a body mass index (BMI), calculated as weight in kilograms divided by the square of height in meters, between 25 and 40. They were eligible for the study if they had IGT according to the World Health Organization criteria, plus impaired fasting glucose (a fasting plasma glucose concentration of between 100 and 140 mg/dL or 5.5 and 7.8 mmol/L) found a number needed to treat of 44 (over 3.3 years) to prevent a major cardiovascular event.

Other studies have shown that life-style changes and metformin can delay the onset of diabetes.