Changes in Insulin Resistance with Different Weight Loss Methods in Patients with Type Two Diabetes Mellitus and Hypertension: A Comparative Clinical Trial

Background: The comparative effects of pharmacological treatment, bariatric surgery, and diet on insulin resistance (IR) remain unclear. Aim: To study the comparative effects of the methods on IR: pharmacologic, bariatric surgery, and very-low-calorie diet (VLCD) in patients with type 2 diabetes mellitus (T2DM) and hypertension. Methods: Design: a 90-day prospective, multicenter, comparative clinical trial including 130 adult patients divided into three groups: Drug, Surgery, and VLCD. Endpoints: HOMA-IR; weight loss; and HbA1c, systolic/diastolic blood pressure (SBP/DBP). Results: At 90 days, weight loss in the Surgery (−19.8%) and VLCD groups (−17.4%) was significant (p < 0.0001), while in the Drug group, the loss was insignificant (−6.5%; p = 0.06). SBP/DBP in the Drug group decreased by −9.5% (p = 0.0002) and −4.1% (p = 0.09), respectively. SBP/DBP in the Surgery group decreased by −13.6% and −10.6%, respectively (p < 0.001), and in the VLCD group, by −23.3% and 21.3%, respectively (p < 0.0001). HOMA-IR in Drug, Surgery, and VLCD groups decreased by −42.2% (p = 0.004), −87.6% (p < 0.0001), and −88.7% (p < 0.0001), respectively. In the Drug group, HOMA-IR did not reach the normal level. Correlation-regression analysis revealed a direct correlation between weight loss and a decrease in HOMA-IR (r = 0.526; F = 33.2, p < 0.0001). HOMA-IR decreases by 65% if weight decreases by 10%; if weight decreases by 25%, then HOMA-IR decreases by 83%. Conclusions: HOMA-IR was associated with weight loss: the greater the weight loss, the lower the HOMA-IR. Weight loss leads to a reduction in the need for antidiabetic/antihypertensive drugs in patients with T2DM and hypertension.