Surrogate Measures of Insulin Resistance in Middle-aged Non-diabetic Subjects

Objective: Insulin resistance has been shown to be a risk factor for type 2 diabetes and cardiovascular disease. The assessment of insulin sensitivity in the clinical practice, however, faces several difficulties. The study proposes to analyze surrogate measures of insulin resistance based on fasting insulin levels in central Romania, and check whether the diagnosis of the metabolic syndrome is an adequate strategy to identify middle-aged persons with reduced insulin sensitivity.
Methods: Anthropometric measurements, metabolic profile, and surrogates measures of insulin sensitivity (GIR, HOMA, QUICKI, FIRI, Belfiore, Bennett, Raynaud, McAuley index) based on fasting insulin levels were assessed in 233 non-diabetic middle aged subjects.
Results: Cutoff values, determined as the lowest quartile of insulin sensitivity for fasting insulin, HOMA, IRI (1/QUICKI), FIRI and Belfiore’s, Bennett’s, Raynaud’s and McAuley’s insulin sensitivity indices were 10.49 mU/L, 2.1, 3.01, 2.32, and 0.03, 1.34, 3.81, 6.29, 5.82. Components of the metabolic syndrome showed moderate but significant correlations with the surrogate measures of insulin resistance (r = 0.22–0.56, p <0.05). HOMA-IR and McAuley indices were the best predictors of clustered cardiometabolic risk factors (AUC – 0.83, 0.81 and 0.82). The metabolic syndrome diagnosis performed well in identifying patients with reduced insulin sensitivity (McAuley 2: sensitivity – 0.78, specificity – 0.84).
Conclusion: Fasting insulin derived insulin sensitivity indices may help the recognittion of insulin resistant states predicting cardiometabolic disorders. Actively looking for insulin resistance by these simple indices, or by diagnosing the metabolic syndrome, those at increased risk can be recognized.