Association between insulin resistance and BMI with FEV in non-hypoxemic COPD out-patients.

Objectives: This study was conducted to determine the impact of insulin resistance using Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) score and BMI in non-hypoxemic out-patients with COPD on FEV using linear and polynomial regressions and to determine their correlation.

Methods: COPD patients of both genders were included after informed consent. Fasting blood sugar and serum insulin were done to calculate HOMA-IR, which were segregated into two groups of ≥ 3 and < 3 labeled insulin resistance present and absent, these were compared with BMI. Patients were segregated into GOLD Grade 1-4 per GOLD Guidelines and compared with HOMA-IR and BMI. Curve and linear regressions, multivariate and univariate analysis of HOMA-IR with BMI, FVC, and FEV were done.

Results: A total of 273 subjects were inducted after informed consent. There was a linear correlation between HOMA-IR and BMI (r 0.498, P < 0.001) and nonlinear correlation between HOMA-IR and FEV1 (r 0. 617, P < 0.001) which showed little evidence of association above FEV1 > 60 predicted, but a clear negative association below that. Significant increase in HOMA-IR was seen from GOLD-2 to 3 and from GOLD-3 to 4 classes. The impact of HOMA-IR on FEV1 was 49.9% (P < 0.001) on FVC was 43.7%.

Conclusions: The results indicate that there is a high prevalence of IR in non-hypoxemic COPD. A nonlinear association is present between FEV1 and HOMA-IR which is most evident with FEV1 <60% predicted.