Effects of aerobic physical exercise in the elderly with type 2 diabetes mellitus

Abstract

The objective of this study was to determine the impact of an aerobic physical exercise program in the treatment of a group of elderly patients with type 2 diabetes mellitus (DM) in relation to metabolic control, physical capacity, quality of life (QOL) and attitudes toward diabetes. Patients were randomly assigned to either an experimental (n=19) or a control (n=20) group. The following measurements were conducted at baseline and after week 16: glycosylated hemoglobin (hbA1c), fructosamine, 3 h oral glucose tolerance test, treadmill test (Balke–Naughton), and a questionnaire on QOL and attitudes toward DM. After the intervention, the experimental group showed a significant decrease of glucose excursion during the oral glucose tolerance test (OGTT) (area under the curve) (16.6±3.8 vs. 15.3±3.1, P<0.05) and an increase in total time on the treadmill (s) (423±207 vs. 471±230, P<0.05). An improvement in the attitudes toward DM was observed in the experimental group (P=0.01) but not in the control group. Female gender, higher body mass index and hbA1c were factors associated with a response to the intervention. This study suggests that physical exercise has significant effects on glucose excursion during an OGTT and exercise tolerance in elderly patients with type 2 DM.

Introduction

Type 2 diabetes mellitus (DM) has been characterized by an increase in hepatic glucose production, a deficit in insulin secretion and an increased resistance to its action (DeFronzo et al., 1992). Studies on normal and middle-aged diabetic subjects have shown that physical exercise results in numerous beneficial adaptations in skeletal muscles, including an increase in the expression of the glucose transporter GLUT 4 thus resulting in an increased sensitivity to the action of insulin (LeBlanc et al., 1981, Goodyear and Kahn, 1998). In the same population, physical exercise of either low or high intensity, was associated with a significant increment in insulin sensitivity (Braun et al., 1995, Mayer-Davis et al., 1998).

The phenomenon of insulin resistance has been shown to characterize type 2 DM in elderly subjects (Meneilly et al., 1996) and in particular in the more obese group (Meneilly and Elliott, 1999). However, limited data are available on the role of physical exercise in the treatment of type 2 DM in the elderly. In a study with a small group of 14 diabetic men who were not on oral antidiabetic agent and who followed a training program over 2 years, Skarfors observed an improvement of physical performance but without observable metabolic change (Skarfors et al., 1987). In a recent study, a support program to promote physical activity failed to measure any change in the amount of physical exercise in an older population with type 2 DM (Samaras et al., 1997). In this respect, a position paper from the American Diabetes Association underlined the importance of physical training in the control of type 2 DM in subjects of all ages (American Diabetes Association, 1997). Two other studies suggested that in patients already taking sulfonylureas, the combination of physical exercise plus the oral agent is significantly more hypoglycemic than either modality of treatment alone (Massi-Benedetti et al., 1996, Gudat et al., 1998). However in daily practice, after the introduction of oral agents to control glycemia in type 2 DM, the role of physical training in the improvement of metabolic control is still not clear.

It has been proposed that concepts related to personal-model beliefs and social-environmental barriers are pertinent to the self-management of DM (Glasgow et al., 1997). A survey study reported that in diabetic subjects, a lower level of physical activity was associated with a lower score on the assessment of the quality of life (QOL) (Glasgow et al., 1997). However, the effects of a structured physical exercise program in an older population with type 2 DM on parameters regarding QOL and attitudes, is an unanswered question.

Consequently, a randomized study was conducted to examine the impact of an aerobic physical exercise program on parameters linked to metabolic control, physical performance, QOL and attitudes in a group of elderly ambulatory patients under treatment for type 2 DM.