Associations between physical fitness and HbA₁c in type 2 diabetes mellitus

• Published in: Diabetologia 2011, Vol.54 (1), p.93-102
• Main Authors: Larose, J, Sigal, R. J, Khandwala, F, Prud'homme, D, Boulé, N. G, Kenny, G. P
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cardiorespiratory fitness; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; exercise; Human Physiology; Internal Medicine; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Randomised controlled trial; Resistance exercise; Strength
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-010-1941-3

Aim/hypothesis In people with type 2 diabetes, exercise improves glucose control (as reflected in HbA₁c) and physical fitness, but it is not clear to what extent these exercise-induced improvements are correlated with one another. We hypothesised that reductions in HbA₁c would be related: (1) to increases in aerobic fitness and strength respectively in patients performing aerobic training or resistance training; and (2) to changes in strength and aerobic fitness in patients performing aerobic and resistance training. Methods We randomly allocated 251 type 2 diabetes patients to aerobic, resistance, or aerobic plus resistance training, or to a sedentary control group. Peak oxygen consumption ( [graphic removed] ), workload, treadmill time and ventilatory threshold measurements from maximal treadmill exercise testing were measured at baseline and 6 months. Muscular strength was measured as the maximum weight that could be lifted eight times on the leg press, bench press and seated row exercises. Results With aerobic training, significant associations were found between changes in both [graphic removed] (p = 0.040) and workload (p = 0.022), and changes in HbA₁c. With combined training, improvements in [graphic removed] (p = 0.008), workload (p = 0.034) and ventilatory threshold (p = 0.003) were significantly associated with changes in HbA₁c. Increases in strength on the seated row (p = 0.006) and in mid-thigh muscle cross-sectional area (p = 0.030) were significantly associated with changes in HbA₁c after resistance exercise, whereas the association between increases in muscle cross-sectional area and HbA₁c in participants doing aerobic plus resistance exercise (p = 0.059) was of borderline significance. Conclusions/interpretation There appears to be a link between changes in fitness and HbA₁c. The improvements in cardiorespiratory fitness with aerobic training may be a better predictor of changes in HbA₁c than improvements in strength.