Post-meal Exercise and Glycemic Control in Aging

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DESCRIPTION (applicant's description): Glucose tolerance declines progressively with aging, and this decline in metabolic resiliency can be attributed primarily to factors secondary to aging, such as changes in body composition and low levels of physical activity. Insufficient insulin secretion is also an important contributor; however, as impaired ¿-cell compensation to aging- and disuse-related insulin resistance may indeed accelerate the risk of developing post-challenge hyperglycemia and consequent type 2 diabetes and cardiovascular disease in older age. The purpose of this proposal is to examine the extent to which different exercise protocols impact post-prandial and 24-h glycemic control (measured using a continuous glucose monitoring system; CGMS) in older people at risk for type 2 diabetes. Specific aims are: 1) To compare the short-term effectiveness of a traditional exercise condition involving 45 min of sustained walking at lower intensity (~3.0 METs) performed in the morning (TEM), with the same condition performed in the afternoon (TEA) on improvements in postprandial and 24-h glycemic control in inactive older people with impaired glucose tolerance (IGT); 2a) To compare the short-term effectiveness of a novel "Eat and Move" exercise condition [EM; 15 min of walking (~3.0 METs) performed 30 min after each of 3 standard meals] with TEM and TEA on improvements in glycemic control in these same older people; and 2b) To determine the influence of sex and of abdominal fat on post-meal exercise-related improvements in post-prandial and 24-h glycemic control in these older men and women. While a post-meal exercise paradigm has been used as an effective strategy for gestational diabetes, its potential among older populations with compromised ¿-cell function has not been studied. The clinical relevance of shorter, but more frequent, bouts of lower-intensity exercise is substantial as older people are far more likely to engage in that type of physical activity on a regular basis. Given the excess disease burden associated with hyperglycemia in older age, and the recognized value of chronic disease prevention, there are enormous public health benefits to designing exercise programs that are enjoyable and effective within the populations needing them the most. PUBLIC HEALTH RELEVANCE: Post-prandial hyperglycemia may represent the rate-limiting factor in slowing the progression from impaired glucose tolerance toward frank type 2 diabetes and cardiovascular disease. Post-meal exercise may be an effective strategy for supplementing endogenous insulin action for improved post-prandial and 24-h glycemic control in older age. The clinical relevance of shorter, but more frequent, bouts of lower-intensity exercise is substantial as older people are far more likely to engage in that type of physical activity on a regular basis. Given the excess disease burden associated with hyperglycemia in older age, and the recognized value of chronic disease prevention, there are enormous public health benefits to designing exercise programs that are enjoyable and effective within the populations needing them the most.