Progressive Resistance Training versus Moderate-Intensity Aerobic Exercise for Glycaemic Control, Skeletal Muscle Mass, Insulin Sensitivity, and Cardiovascular Risk Reduction in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) affects over 101 million adults in India, constituting the world's largest absolute diabetes burden, with exercise therapy representing an underutilised yet evidence-supported pillar of glycaemic management alongside pharmacological intervention. While aerobic exercise is the traditional guideline-endorsed exercise modality for T2DM, progressive resistance training (PRT) offers mechanistically distinct pathways to glycaemic improvement through skeletal muscle glucose transporter (GLUT4) upregulation, increased insulin-independent glucose disposal via skeletal muscle mass accretion, and enhanced basal metabolic rate. Comparative evidence from well-powered trials in the Indian population — who demonstrate the 'thin-fat' phenotype characterised by low muscle mass and high adiposity at moderate BMI — is lacking. This sixteen-week randomised controlled trial enrolled 280 adults with T2DM (aged 35–65 years, HbA1c 7.0–10.0%) across three JIPMER-affiliated diabetes clinics in Puducherry and Tamil Nadu, randomised to Progressive Resistance Training (PRT, n=95), Moderate-Intensity Aerobic Exercise (MIAE, n=95), or Combined PRT plus MIAE (COMB, n=90). The COMB group achieved the greatest HbA1c reduction (−1.6%, p<0.001) and combined skeletal muscle index improvement (+1.4 kg/m²) with fat mass reduction (−4.8%). PRT alone produced superior skeletal muscle mass gains (+1.8 kg lean mass) and HOMA-IR improvement (−2.4 units) compared to MIAE alone, while MIAE achieved greater VO₂max improvement (+6.8 mL/kg/min). These results challenge the aerobic-exercise primacy in T2DM guidelines and support PRT as an equally effective and potentially more appropriate exercise modality for the low muscle mass Indian diabetic phenotype.