Whey Protein and Resistance Training Improves Insulin Resistance in Older Men With Type 2 Diabetes
A new RCT finds 12 weeks of lifting paired with whey protein significantly reduced HOMA-IR, even in men who had lived with the disease for over a decade
Older men with Type 2 diabetes who added whey protein to a 12-week resistance training program saw a significant improvement in insulin resistance, according to a new triple-blind randomised controlled trial published in Aging Clinical and Experimental Research. The training boosted strength across the board, but neither protein nor carbohydrate supplementation added extra muscle size or improved blood sugar markers beyond what training alone produced.
For the nearly 800 million people projected to have Type 2 diabetes by 2045, finding low-cost, drug-free ways to manage the disease is becoming urgent. This study is one of the few to test supplementation strategies specifically in older men with the disease.
Aim
Researchers wanted to know whether adding whey protein or maltodextrin to a structured resistance training program would improve muscle strength, muscle size, blood sugar control, and blood lipid levels in older men with Type 2 diabetes.
Methods
60 men aged 65 to 79 with Type 2 diabetes were split into three groups:
Whey protein group: 20 g of whey protein after each session
Maltodextrin group: 20 g of maltodextrin after each session
Control group: colored water (placebo)
All participants followed the same resistance training program for 12 weeks, training twice per week. Each session included six exercises (leg press, calf raise, leg curl, chest press, rowing, and abdominal machine), performed as 3 sets of 8 to 12 reps. Load progression was guided by the OMNI perceived exertion scale, and a 1RM test was used to set starting loads.
The study was triple-blind: the participants, the trainers, and the assessors did not know which supplement each participant was taking. Only the nutritionist who administered the supplements knew the group assignments.
Key measurements taken before and after the 12 weeks included:
Insulin resistance via HOMA-IR
Glycated hemoglobin (HbA1c) and fasting glucose
Blood lipid levels (cholesterol, HDL, LDL, triglycerides)
Muscle thickness of the biceps brachii and vastus lateralis via ultrasound
Strength progression tracked through training loads
Results
The standout finding was that the whey protein group showed a significant reduction in HOMA-IR, the marker of insulin resistance, while the maltodextrin and control groups did not. This suggests early improvements in insulin sensitivity in the protein group.
Other key results: