Background: The homeostasis assessment model for insulin resistance (HOMA-IR) estimates insulin resistance using basal insulin and glucose values and has a good concordance with values obtained with the euglycemic clamp. However it has a high variability that depends on environmental, genetic and physiologic factors. Therefore it is imperative to establish normal HOMA values in different populations.
Aim: To report HOMA-IR values in Chilean elderly subjects and to determine the best cutoff point to diagnose insulin resistance.
Material and methods: Cross sectional study of 1003 subjects older than 60 years of whom 803 (71% women) did not have diabetes. In 154 subjects, an oral glucose tolerance test was also performed. Insulin resistance (IR) was defined as the HOMA value corresponding to percentile 75 of subjects without over or underweight. The behavior of HOMA-IR in metabolic syndrome was studied and receiver operating curves (ROC) were calculated, using glucose intolerance defined as a blood glucose over 140 mg/dl and hyperinsulinemia, defined as a serum insulin over 60 microU/ml, two hours after the glucose load.
Results: Median HOMA-IR values were 1.7. Percentile 75 in subjects without obesity or underweight was 2.57. The area under the ROC curve, when comparing HOMA-IR with glucose intolerance and hyperinsulinemia, was 0.8 (95% confidence values 0.72-0.87), with HOMA-IR values ranging from 2.04 to 2.33.
Conclusions: HOMA-IR is a useful method to determine insulin resistance in epidemiological studies. The HOMA-IR cutoff point for insulin resistance defined in thi spopulation was 2.6.