Background: Insulin resistance has been recognized as a major factor in the development of non-alcoholic fatty liver disease (NAFLD). The association between insulin resistance and NAFLD, as a risk factor independent of obesity has been less well established. This study aims to determine presence of insulin resistance and components of metabolic syndrome in non-obese patients with NAFLD.

Methods: 150 patients (mean age 42.25 ± 10.50 y; 115 (76%) male, 35 (24%) female) diagnosed with NAFLD participated in the study. We measured body mass index (BMI), waist circumference (WC), waist hip ratio (WHR), fasting lipid profile, fasting glucose, fasting insulin, and liver function. Insulin resistance was calculated using the homeostasis model of assessment (HOMA) formula. Insulin resistance was arbitrarily considered altered when it was >1.64.

Results: 120 (80%) of the 150 patients were obese (BMI >23) according to the Asia Pacific criteria. 40 (30%) had metabolic syndrome. 97.5% (117/120) had insulin resistance with mean HOMA-insulin resistance (IR) of 10.9±5.3. Thirty (20%) were non-obese; of these, 7 had central obesity (WC > 90 cm for men, > 80 cm for women). Twenty-three (15.3%) patients were lean NAFLD with BMI 21.6±1.5, WC 82.9±4.7 (BMI < 23, WC < 90 cm in men and < 80 cm in women) 80% of these 23 (18/23) had insulin resistance with mean HOMA-IR of 3.4±.1.9. Only 4 (17%) did not have any component of metabolic syndrome.

Conclusion: Insulin resistance often associated with metabolic syndrome is common and plays a key role amongst lean Indian patients with non-alcoholic fatty liver disease.