Effect of resistance training combined with carbohydrate and protein supplementation on the HOMA-IR, glycemic, lipid profile and hypertrophy of older adults with Type II Diabetes: secondary data analysis of a triple-blind RCT

Abstract

Introduction

Type 2 diabetes mellitus (T2DM) is a prevalent chronic disease associated with major health complications, including cardiovascular risk.

Objective

To evaluate the effects of resistance training (RT) combined with protein or carbohydrate supplementation on muscle strength, hypertrophy, and glycemic and lipid profiles in older adults with T2DM.

Methods

A triple-blind randomized clinical trial was conducted with 60 men with T2DM, allocated into three groups: Protein Group (20 g whey protein), Maltodextrin Group (20 g maltodextrin), and Control Group (colored water). All participants completed a 12-week RT program performed twice weekly. Each session included six exercises, with three sets of 8–12 repetitions, guided by subjective perception of effort. Muscle strength progression was monitored through training loads. Glycemic response, HOMA-IR, and lipid profile were analyzed, while muscle thickness of the biceps brachii and vastus lateralis was measured using ultrasound.

Results

The Protein Group showed a significant reduction in HOMA-IR (p = 0.03), indicating improved insulin resistance. Lipid profile variables showed no significant changes across groups. Most exercises demonstrated significant load progression, except rowing and standing curls. Muscle thickness did not show significant differences in either muscle evaluated. RT improved muscle strength regardless of supplementation type but did not produce significant hypertrophy. Protein supplementation significantly reduced HOMA-IR, indicating early improvements in insulin sensitivity, whereas carbohydrate supplementation showed no metabolic effect. Lipid profile parameters remained unchanged, and no significant changes were observed in HbA1c or fasting glycemia.