METFORMIN AND IMPROVEMENT OF THE HEPATIC INSULIN RESISTANCE INDEX INDEPENDENT OF ANTHROPOMETRIC CHANGES

Objective: To determine the change in the hepatic insulin resistance index (HIRE) after metformin treatment. Methods: In this retrospective cohort study, Mexican mestizo patients with a body mass index (BMI) of 25 kg/m(2) or greater were evaluated. Participants were classified into 2 groups: patients who received metformin and patients who did not. Both groups were followed up for a median of 6 months (range, 4-10 months). The HIRI was calculated at baseline and at follow-up in both groups. We evaluated the independent effect of metformin on HIRI after adjustment for the difference in basal and final values (DELTA) of BMI, waist circumference, glucose, and insulin. Results: A total of 71 patients were enrolled (51 [7270] female). Forty-one patients received metformin and 30 patients did not. Mean age was 36.3 12.2 years and mean BMI was 42.2 +/- 10.7 kg/m(2). After metformin treatment, HIRI significantly decreased from 38 +/- 10.7 to 34.7 +/- 9.5 (P = .03). In contrast, the control group had a nonsignificant increase in HIRI (37.6 +/- 11.7 to 40.0 +/- 14.0, P = .22). Weight significantly decreased in both groups (group. 1: 114.6 +/- 33.8 kg to 107.6 +/- 28.9 kg, P<.01; group 2: 104.8 +/- 28.5 kg to 98.9 +/- 26.0 kg, P<.01). After BMI adjustment, the total metformin dosage correlated negatively with HIRI (r = -0.36, P = .03). Using a linear regression model (F = 6.0, r(2) = 0.37, P = .002) adjusted for DELTA BMI and DELTA waist circumference, the administration of metformin resulted in independent improvement in the HIRI level (standardized beta = -0.29, t = -2.0, P = .04). Conclusions: Metformin improves HIRI independently of anthropometric changes. In persons with elevated HIRI levels, metformin may be considered among the treatment options. (Endocr Pract. 2012;18:8-16)