Insulin resistance is an independent correlate of increased urine albumin excretion: a cross‐sectional study in Iranian Type 2 diabetic patients

Aims To assess the association of insulin resistance with increased urinary albumin excretion (UAE) in a cohort of Iranian Type 2 diabetic patients. Methods Three hundred and sixty‐one men and 472 women with Type 2 diabetes were enrolled from three different outpatient clinics (Tehran, Iran) during the period 2005–2008. Patients with obstructive uropathy, severe heart failure, liver disease, cancer, autoimmune disease and macroalbuminuria were not included. Microalbuminuria (MA; defined as UAE ≥ 30 mg/day) was found in 242 (29.1%) patients; 591 (70.9%) subjects had normoalbuminuria (UAE < 30 mg/day). Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HOMA‐IR). Results HOMA‐IR index values were higher in subjects with MA than those with normoalbuminuria (P < 0.00001). Adjusted values (for age, sex and duration of diabetes) of UAE and HOMA‐IR were 11.81 ± 7.51 (mg/day) and 3.30 ± 2.21 in normoalbuminuric and 75.36 ± 55.57 (mg/day) and 4.98 ± 3.22 in the MA group, respectively (P < 0.00001 for all). Multiple regression analysis showed that UAE was predicted by HOMA‐IR, independently of age, duration of diagnosed diabetes, triglycerides, waist circumference, metabolic control, blood pressure and related treatments (P < 0.00001). When patients were categorized into quartiles of HOMA‐IR, those of the fourth quartile (i.e. the most insulin resistant) were at a higher risk of increased UAE than other quartiles [odds ratio (OR) 3.7 (95% confidence intervals 2.7–6.2)]. Conclusions In Iranian Type 2 diabetic patients, albuminuria was strongly associated with insulin resistance. HOMA‐IR is an independent predictor of UAE.