Many Americans have pre-diabetes and should be considered for metformin therapy

Abstract

Objective: To determine the proportion of the American population who would merit metformin treatment, according to recent American Diabetes Association (ADA) consensus panel recommendations to prevent or delay the development of diabetes.

Research design and methods: Risk factors were evaluated in 1,581 Screening for Impaired Glucose Tolerance (SIGT), 2,014 Third National Health and Nutrition Examination Survey (NHANES III), and 1,111 National Health and Nutrition Examination Survey 2005-2006 (NHANES 2005-2006) subjects, who were non-Hispanic white and black, without known diabetes. Criteria for consideration of metformin included the presence of both impaired fasting glucose (IFG) and impaired glucose tolerance (IGT), with > or =1 additional diabetes risk factor: age <60 years, BMI > or =35 kg/m(2), family history of diabetes, elevated triglycerides, reduced HDL cholesterol, hypertension, or A1C >6.0%.

Results: Isolated IFG, isolated IGT, and IFG and IGT were found in 18.0, 7.2, and 8.2% of SIGT; 22.3, 6.4, and 9.4% of NHANES III; and 21.8, 5.0, and 9.0% of NHANES 2005-2006 subjects, respectively. In SIGT, NHANES III, and NHANES 2005-2006, criteria for metformin consideration were met in 99, 96, and 96% of those with IFG and IGT; 31, 29, and 28% of all those with IFG; and 53, 57, and 62% of all those with IGT (8.1, 9.1, and 8.7% of all subjects), respectively.

Conclusions: More than 96% of individuals with both IFG and IGT are likely to meet ADA consensus criteria for consideration of metformin. Because >28% of all those with IFG met the criteria, providers should perform oral glucose tolerance tests to find concomitant IGT in all patients with IFG. To the extent that our findings are representative of the U.S. population, approximately 1 in 12 adults has a combination of pre-diabetes and risk factors that may justify consideration of metformin treatment for diabetes prevention.

Figure 1

Prevalence of metformin indication, stratified by glucose tolerance category. Metformin is indicated per the ADA consensus statement criteria of the presence of both IFG and IGT and one of the following diabetes risk factors: age <60 years, BMI ≥35 kg/m², family history of diabetes, elevated triglycerides, reduced HDL cholesterol, and A1C >6.0% (8). Risk factors for diabetes that were not specifically defined by the ADA were categorized according to the AHA/NHLBI diagnostic criteria for metabolic syndrome (12): presence of hypertension by history, systolic blood pressure >130 mmHg or diastolic blood pressure >85 mmHg, triglyceride level ≥150 mg/dl, and HDL cholesterol <40 mg/dl in men and <50 mg/dl in women. Glucose tolerance categories are as follows: IFG 100–109, FPG levels 100–109 mg/dl and 2-h postchallenge plasma glucose <140 mg/dl; IFG 110–125, FPG 110–125 mg/dl and 2-h postchallenge plasma glucose <140 mg/dl; all IFG, isolated IFG (FPG 100–125 mg/dl and 2-h postchallenge plasma glucose <140 mg/dl); IGT, isolated IGT; and IFG 100–125 + IGT, all IFG and IGT.