Muscle adaptations and glucose control after physical training in insulin‐dependent diabetes mellitus

Abstract

Six men and three women with insulin-dependent diabetes (without complications) participated in physical training three times a week for 20 weeks. Physical training did not change the concentration of fasting blood-glucose, glucose excretion in urine or glucosylated haemoglobin (HbA1). However, the glucose disposal rate during euglycaemic clamp increased after training. In two patients a minor reduction of insulin dosage was necessary to alleviate slight hypoglycaemic episodes. The training resulted in significant increases in quadriceps isometric and dynamic strength and endurance. Maximal oxygen uptake increased by 8%, the activity of glycolytic enzymes in vastus lateralis muscle by 47% for hexokinase, and 30% for tri-osephosphate dehydrogenase and 25% for lactic dehydrogenase, the activity of oxidative enzymes by 42% for citrate synthase and 46% for 3-hydroxy-acyl-CoA-dehydrogenase. The glycogen concentration in the vastus lateralis muscle did not change significantly. Lipoprotein lipase activity did not change in muscle, nor in adipose tissue. The mean muscle fibre area increased by 25% and the area of FTa fibres by 30%. The new formation of capillaries around different muscle fibres was significant for FTb fibres (26%). The proliferation of capillaries, however, appeared to be insufficient to cope with the increased area of muscle fibres. As a result, the mean area of muscle fibre supplied by one capillary (a measure of diffusion distance) significantly increased after training for FTa fibres. It is concluded that with the exception of deficient proliferation of capillaries, patients with insulin-dependent diabetes mellitus show a normal central and peripheral adaptation to physical training. Physical training does not apparently improve blood glucose control in most cases, despite an increased insulin sensitivity.

Athletes With IDDM Exhibit Impaired Metabolic Control and Increased Lipid utilization With No Increase in Insulin Sensitivity

“…However, the athletes had worse glycemic control and took a smaller insulin dose than did the sedentary patients. Some, but not all (31), previous studies have reported either a small decrease in insulin requirements during programmed daily physical training (2) or an inverse relationship between insulin dose and Vo 2ni ax (32). The smaller insulin dose requirement in the athletes may be partly due to repeated acute exercise periods, but it may also be intentional to avoid hypoglycemia during the periods of training and competition.…”

Muscular Endurance in Long-Term IDDM Patients

“…IDDM patients adapt normally to exercise training with increased muscular strength and endurance and with a corresponding increase in cross-sectional muscle fiber area (12). However, short-term dynamic muscular endurance has not been evaluated thoroughly in diabetic patients, and its relationship to neuropathic complications and metabolic control is unknown.…”

Skeletal Muscle Metabolism in the Pathology and Treatment of Type 1 Diabetes

“…Deficient capillary formation in response to exercise and training has also been noted in diabetic patients [130,131] which may relate to secondary microvascular and macrovascular complications. To counteract vascular abnormalities in diabetes, stroke and peripheral arterial occlusive disease, pro-angiogenic therapies using molecules such as VEGF are being developed.…”