Combined training improves HbA1c and glucose in middle-aged and older adultsCombined aerobic and resistance training improves blood sugar levels

This meta-analysis evaluated the efficacy of exercise interventions on glycemic and metabolic markers in a population of 1853 middle-aged and older adults (aged 45 years and older). The study compared combined training (aerobic plus resistance training) against several control conditions, including aerobic training alone and resistance training alone. The primary outcome measured was HbA1c levels, with secondary outcomes including HOMA-IR, glucose, insulin, and various lipid outcomes. The evidence for HbA1c results is categorized as moderate-certainty, while other outcomes are categorized as low to very low certainty.

Regarding the primary outcome, combined training resulted in a significant improvement in HbA1c compared with control conditions (Hedges' g = -0.44; p < 0.01). When comparing combined training specifically to resistance training, a small additional improvement in HbA1c was observed. Secondary outcomes also showed significant improvements for combined training compared to control conditions. Specifically, HOMA-IR showed a significant improvement (Hedges' g = -0.59; p = 0.01), with notably greater improvements observed in overweight and obese individuals. Glucose levels also showed significant improvement compared with control conditions (Hedges' g = -0.81; p = 0.03).

Data regarding safety and tolerability were not reported in the included studies. Consequently, specific adverse event rates, serious adverse events, or discontinuation rates are not available for clinical assessment. The study notes that evidence for insulin and lipid outcomes was inconclusive, and prediction intervals for these specific outcomes were wide, suggesting a lack of precision in those data points.

When comparing these results to the broader landscape of metabolic health interventions, the findings confirm that any structured exercise program provides significant benefits over sedentary control conditions. However, the evidence does not support a consistent, large-scale advantage of combined training over single-modality exercise for this specific population. The finding of a small additional improvement in HbA1c over resistance training should be interpreted with caution due to the limited statistical power for that specific comparison.

Several methodological limitations were identified. The analysis noted limited statistical power when comparing combined training directly against resistance training. Furthermore, potential differences in total exercise volume between the combined and resistance training groups may confound the results. The inclusion of several outcomes, specifically insulin and lipid markers, was underpowered, leading to inconclusive results in those categories.

Clinically, these results suggest that combined training is an effective intervention for improving glycemic outcomes, including HbA1c and glucose, in middle-aged and older adults. While combined training may offer a slight edge over resistance training alone for HbA1c, the evidence is not robust enough to mandate combined training over aerobic training for all patients. Practitioners can confidently recommend combined training as a means to improve HOMA-IR and glucose. However, the specific benefits regarding lipid profiles and insulin levels remain unclear due to the current data limitations. Future research is needed to determine if specific volumes or intensities of combined training provide superior outcomes over single-modality programs and to clarify the impact on lipid profiles.