DISTRIBUTION OF FASTING SERUM-INSULIN MEASURED BY ENZYME-IMMUNOASSAY IN AN UNSELECTED POPULATION OF 4,032 INDIVIDUALS - REFERENCE VALUES ACCORDING TO AGE AND SEX

As hyperinsulinaemia has been shown to be a risk factor for non-insuli n-dependent diabetes, cardiovascular disease and hypertension, the mea surement of serum insulin levels may provide an additional early scree ning test for these diseases. Biological assaying of insulin is now fa cilitated by the IMx-Abbott kit, an enzyme immunoassay which does not cross-react with proinsulin and thus provides more spe cific insulin d etermination than conventional methods. Fasting insulin concentrations were determined in a population of 4,032 men and women 30 to 64 years of age, all volunteers for a medical check-up. Concentrations were sl ightly higher for men in all age-classes (median values of 5.9 and 5.4 mu U/ml respectively for men and women). Although significant differe nces were found in serum insulin concentrations between the four age-c lasses for men and women, there were no significant differences betwee n the three age-classes for men up to 59 years (median: 5.8 mu U/ml, 9 5th percentile 14.0 mu U/ml) or between the two age classes for women up to 49 years (5.2, 12.5). Fasting concentrations were increased abov e these age thresholds : men (6.4, 15.6), women (5.6, 14.0). The refer ence population consisted of 3,081 non-diabetic, glycosuria-negative s ubjects with a body mass index and glucose concentration lower than th e 95th percentiles for their age and sex. The reference values for fas ting insulin concentrations were: 1) women 30-49 years: median 5.1 mu U/ml (95 % confidence interval: 4.9-5.3), 95th percentile 11.2 mu U/ml (10.9-11.9); and 2) men 30-64 years and women 50-64 years: median 5.6 mu U/ml (5.4-5.7), 95th percentile 12.6 mu U/ml (12.0-13.0).