Basal-State Hyperinsulinemia in Healthy Normoglycemic Adults Is Predictive of Type 2 Diabetes Over a 24-Year Follow-Up

OBJECTIVE We examined the predictive value of hyperinsulinemia in the basal state on the 24-year progression from normoglycemia to dysglycemia. RESEARCH DESIGN AND METHODS A sample of 515 normoglycemic men and women were studied again after 24 years for glycemic status. RESULTS Half of the participants developed dysglycemia: 11.1% progressed to impaired fasting glucose (IFG), 9.9% to impaired glucose tolerance (IGT), 4.5% to both IFG and IGT, and another 24.3% to type 2 diabetes. Elevated levels of overnight fasting (basal) insulin, triglycerides, BMI > or =27 kg/m(2), fasting blood glucose, blood pressure, North African or Yemenite background, and male sex each favored conversion to dysglycemia after 24 years. In multiple ordered logistic regression analysis, the most significant predictor of progression to dysglycemia was hyperinsulinemia (upper quintile), after adjusting for BMI, ethnic origin, sex, age, smoking, physical activity, blood pressure, and triglycerides. CONCLUSIONS Basal hyperinsulinemia in normoglycemic adults constitutes an independent risk factor for developing dysglycemia over 24 years.