DIETARY-FAT PREDICTS CONVERSION FROM IMPAIRED GLUCOSE-TOLERANCE TO NIDDM - THE SAN-LUIS-VALLEY-DIABETES-STUDY

OBJECTIVE - To determine if dietary fat intake measured at a baseline exam in subjects with impaired glucose tolerance (IGT) predicted the s ubsequent development of non-insulin-dependent diabetes mellitus (NIDD M). RESEARCH DESIGN AND METHODS - Based on an oral glucose tolerance t est (OGTT) (World Health Organization criteria), we identified 134 eli gible subjects with IGT from a geographically based sample of subjects with no prior history of diabetes. One to three years after the basel ine exam, 123 subjects (92%) had a repeat OGTT. Diet was assessed by a 24-h diet recall reported before the baseline OGTT. RESULTS - The mea n percentage of energy eaten as fat was 43.4% in 20 people subsequentl y developing NIDDM compared with 40.6% in 43 people remaining IGT and 38.9% in 60 subjects who subsequently reverted to normal glucose toler ance. In comparing the 20 subjects who developed NIDDM with the 103 wh o remained IGT or normal, an increase in fat intake of 40 g/day was as sociated with an increase in risk of NIDDM of 3.4-fold (95% confidence interval [CI] 0.8-13.6) adjusted for energy intake, age, sex, ethnici ty, and obesity. The odds ratio increased to sixfold (95% CI 1.2-29.8) after adjustment for fasting glucose, insulin, and 1-h insulin. CONCL USIONS - Fat consumption significantly predicts NIDDM risk in subjects with IGT after controlling for obesity and markers of glucose metabol ism.