Impact of short-term exercise training intensity on β-cell function in older obese adults with prediabetes.
Level 2 - randomized trial
Randomized controlled trial
PubMed 30307821 · doi:10.1152/japplphysiol.00680.2018
What was done
Thirty-one older adults with obesity and prediabetes (mean age 61.4 ± 2.5 years, BMI 32.1 ± 1.0 kg/m²) were randomized to 2 weeks of daily 60-minute work-matched exercise: continuous moderate training (CONT, 70% peak heart rate) or interval training (INT, alternating 3 minutes at 90% and 3 minutes at 50% peak heart rate). A 75-g 2-hour oral glucose tolerance test was performed after an overnight fast to measure plasma glucose, insulin, C-peptide, free fatty acids, active GLP-1, and GIP. Tissue-specific insulin sensitivity (skeletal muscle, hepatic, adipose) and β-cell function via glucose-stimulated insulin secretion and the disposition index (DI) were calculated.
What was found
Both CONT and INT increased skeletal muscle-derived DI (P < 0.05), but neither changed hepatic- or adipose-derived DI. Early-phase active GLP-1 increased significantly in both groups (P < 0.001), while fasting active GLP-1 showed a non-significant reduction trend (P = 0.08). Fasting GIP increased after CONT but decreased after INT (P = 0.02). Reductions in total glucose area under the curve correlated with increases in early-phase (r = -0.52, P = 0.002) and total-phase (r = -0.50, P = 0.003) skeletal muscle DI.
Why it matters
Short-term exercise improves β-cell function and incretin response in older adults with prediabetes prior to weight loss, with improvements occurring similarly regardless of whether exercise is continuous or interval-based when total work is matched.
Limits
The study had a small sample size (n = 31) and a short duration of two weeks. It lacked a non-exercise control group to account for repeated-testing effects, and the abstract did not report absolute effect sizes or baseline-to-post raw numerical values for metabolic parameters.
Cited by
- supports Physical activity enhances muscle insulin sensitivity, leading to lower insulin secretion in response to a given quantity of carbohydrate.