PREVALENCE OF INSULIN-RESISTANCE IN METABOLIC DISORDERS - THE BRUNECKSTUDY

The prevalence of insulin resistance in the most common metabolic diso rders is still an undefined issue. We assessed the prevalence rates of insulin resistance in subjects with impaired glucose tolerance (IGT), NIDDM, dyslipidemia, hyperuricemia, and hypertension as identified wi thin the frame of the Bruneck Study. The study comprised an age- and s ex-stratified random sample of the general population (n = 888; aged 4 0-79 years). Insulin resistance was estimated by homeostasis model ass essment (HOMA(IR)), preliminarily validated against a euglycemic-hyper insulinemic clamp in 85 subjects. The lower limit of the top quintile of HOMA(IR) distribution (i.e., 2.77) in nonobese subjects with no met abolic disorders (n = 225) was chosen as the threshold for insulin res istance. The prevalence of insulin resistance was 65.9% in IGT subject s, 83.9% in NIDDM subjects, 53.5% in hypercholesterolemia subjects, 84 .2% in hypertriglyceridemia subjects, 88.1% in subjects with low HDL c holesterol, 62.8% in hyperuricemia subjects, and 58.0% in hypertension subjects. The prevalence of insulin resistance in subjects with the c ombination of glucose intolerance (IGT or NIDDM), dyslipidemia (hyperc holesterolemia and/or hypertriglyceridemia and/or low HDL cholesterol) , hyperuricemia, and hypertension (n = 21) was 95.2%. In isolated hype rcholesterolemia, hypertension, or hyperuricemia, prevalence rates of insulin resistance mere not higher than that in nonobese normal subjec ts. An appreciable number of subjects (n = 85, 9.6% of the whole popul ation) was insulin resistant but free of IGT, NIDDM, dyslipidemia, hyp eruricemia, and hypertension. These results from a population-based st udy documented that 1) in hypertriglyceridemia and a low HDL cholester ol state, insulin resistance is as common as in NIDDM, whereas it is l ess frequent in hypercholesterolemia, hyperuricemia, and hypertension; 2) the vast majority of subjects with multiple metabolic disorders ar e insulin resistant; 3) in isolated hypercholesterolemia, hyperuricemi a, or hypertension, insulin resistance is not more frequent than can b e expected by chance alone; and 4) in the general population, insulin resistance can be found even in the absence of any major metabolic dis orders.