Abstract
BACKGROUND: The association between prediabetes as currently defined and incident diabetes in populations with widespread obesity, insulin resistance syndrome, and diabetes is not well defined. In this article, diabetes risk factors and incidence rates in American Indians (AI) with prediabetes are examined. METHODS: A total of 1677 AI who were nondiabetic at baseline was examined during a median 7.8-year follow-up as part of the Strong Heart Study (SHS). Risk factors for incident diabetes were measured. Prediabetes was defined according to American Diabetes Association 2003 criteria as having impaired glucose tolerance (IGT) (2-h plasma glucose [2-h PG] >or= 140 mg/dL but < 200 mg/dL) and/or impaired fasting glucose (IFG) (fasting plasma glucose [FPG] >or= 100 mg/dL but < 126 mg/dL). RESULTS: Prediabetes was identified by FPG alone in 87.5%. Diabetes incidence in those with baseline prediabetes was 66.1/1000 person-years, with a hazard ratio (HR) of 2.35 (95% conference interval: 1.84-3.01), compared with participants with normal glucose tolerance (NGT) at baseline. Elevated A(1c), 2-h PG, and fasting insulin (FI); albuminuria; and obesity were significantly associated with conversion from prediabetes to diabetes. Younger age, elevated FI (or body mass index [BMI] in models without FI), and less physical activity were significantly associated with conversion from NGT. CONCLUSIONS: Prediabetes is an independent predictor of conversion to type 2 diabetes in AI, and most can be identified through a fasting glucose measure. Measures of obesity, A(1c), FPG, 2-h PG, FI, albuminuria, and insulin resistance (IR) help predict this conversion. Obesity is a modifiable risk factor. Strategies to reduce obesity should be emphasized in individuals with prediabetes.