Insulin Resistance and β-Cell Function of Lean versus Overweight or Obese Filipino Patients with Newly Diagnosed Type 2 Diabetes Mellitus

Objectives. To compare the level of insulin resistance and beta-cell function between lean and overweight/obese Filipino patients with newly diagnosed type 2 diabetes mellitus (T2DM). Methodology. This was a cross-sectional analytical study including newly diagnosed T2DM Filipino patients from St. Luke's Medical Center - Quezon City. The patients were classified as either lean or overweight/obese. Age, sex, smoking history, anthropometric measures and blood pressure were obtained. Insulin resistance and beta-cell function were determined using the homeostasis model assessment (HOMA). The original model (HOMA1) and the updated model (HOMA2) were used. Results. A total of 80 subjects were included. There were 40 subjects in each group. The overweight/obese subjects had significantly higher mean insulin resistance (HOMA1-IR 9.8 +/- 11.7, HOMA2-1R 3.0 +/- 2.0) compared to the lean group (HOMA1-IR 2.9 +/- 1.5, HOMA2-IR 1.3 +/- 0.5). This was consistent in both HOMA1 and HOMA2 (p-values=0.001 and <0.001, respectively). The mean 8 -cell function of the overweight/obese patients was significantly higher than the lean subjects when using HOMA1 (lean=57.8 +/- 35.5, overweight/obese=93.6 +/- 66.4, p-va/ue=0.003), but not in HOMA2 (lean=57.6 +/- 30.5, overweight/obese=74.8 +/- 45.7, p-value=0.051). Overweight/obesity increased HOMA1-IR by 4.0 and HOMA1-B by 46.1 (p-values= 0.002 and <0.001, respectively). Through the use of HOMA2, overweight/ obesity increased HOMA2-1R by 1.4 and HOMA2-B by 29.1 (p-va/ues<0.001). Being overweight/obese was also associated with significantly higher odds for developing greater insulin resistance (HOMA1-IR adjOR = 5.6, 95%Cl= 11-19.2, p-value=0.005; HOMA2-IR adjOR=10.9, 95%C1=3.4-34.9, p-value<0.001) and lower odds for a decreased 13-cell function (HOMA1-B adjOR = 0.2, 95%Cl = 0.05-0.9, p-vatue=0.033; HOMA2-B adjOR=0.2, 95%CI=0.04-0.9, p-value=0.043) compared to being lean. Conclusion. Newly diagnosed overweight/obese T2DM had higher mean insulin resistance and 13-cell function compared to lean T2DM. Overweight/obesity was also associated with higher odds of developing insulin resistance and lower odds for a decreased 13-cell function compared to being lean. The overweight/obese T2DM group also had worse metabolic profile manifested by higher FPG, HbA1c, SGPT and blood pressures compared to the lean T2DM group.