Insulin resistance quantification by fasting insulin plasma values and HOMA index in a non-diabetic population

Our goal was to determine the prevalence of insulin resistance (IR) by means of fasting insulin plasma values and the HOMA index,and to analyse the relation of these parameters with other components of the metabolic syndrome. We studied 292 non-diabetic individuals, aged between 20 and 65 years, randomly selected from subjects attending an outpatient care center (Valencia-Spain-metropolitan area). 97 subjects who lacked clinical and biological criteria of IR were selected. In addition to calculating the HOMA index, anthropometric parameters, plasma lipids values, fasting glucose and insulin plasma levels were measured by standard methods in all subjects. In the subgroup of 97 subjects without clinical and biological criteria of IR, we established a diagnosis of IR when the fasting plasma insulin value was >= 16.7 mU/l or the HOMA index was >= 3.8. Cut-off points of the percentil 90th of this subgroup were taken into account. In the whole group,the prevalence of IR (HOMA >= 3.8) was 31.8%, with a higher frequency in men compared to women. In addition to fasting plasma insulin values and HOMA index, the best clinical and biochemical indicators of IR were fasting plasma glucose levels, BMI and triglycerides (TG) plasma values. Thus, the odds ratio for insulin resistance was 5.9 for a glycemia >= 110 mg/dl, 2.6% for BMI >= 25 kg/m(2) and 2.2 for triglycerides >= 150 mg/dl.