February 28 — 29, 2008 Advisory Committee Meeting Minutes

Subcommittee Report: Metabolic Health

Judith Regensteiner, Ph.D., led discussion on physical activity and metabolic health. The subcommittee focused on the following research questions:

1. What is the relationship between physical activity and prevention of metabolic syndrome/insulin resistance?

   Conclusions
   There is an inverse dose-response association between physical activity level (and fitness) and the development of metabolic syndrome in adults. The minimal amount of activity ranges between 120 – 180 minutes per week of moderate intensity physical activity; however, many studies support 150 minutes per week. The pattern is similar in men and women but there is a need for more data examining metabolic syndrome in youth and across ethnicities.

2. What is the relationship between physical activity and prevention and treatment of Type 2 Diabetes (T2DM)?

   Conclusions
   There is strong RCT data as well as observational, longitudinal, cross-sectional data and meta-analyses. The data presents strong evidence that physical activity has a major role in the prevention of T2DM and is consistent in both men and women. The data also suggests that 30 minutes per day of moderate intensity exercise appears to be an effective dose although it is not entirely clear. The independent role of physical activity in the prevention of T2DM as well as the effects across different ethnic groups is not clear.

3. What is the relationship between physical activity and prevention of macrovascular complications of T2DM?

   Conclusions
   The group interpreted longitudinal, cross-sectional and observational studies as well as 1 meta-analysis. From the data it appears exercise is particularly beneficial for reducing cardiovascular risks. Dose-response studies suggest at least 2 hours per week of moderate exercise is required for significant benefits. The benefit may reach a peak level at 3 – 7 hours; however, more hours show a flattening of benefit. The studies also seem to support a recommendation of moderately vigorous exercise. Aerobic or combined aerobic/resistance exercise seem best. There may be differences in the dose-response between genders but more study is required. There is no data on ethnic differences.

4. What is the relationship between physical activity and Type 1 Diabetes?

   Conclusions
   There is no evidence that physical activity helps prevent Type 1 Diabetes. There are many small interventional studies; however, they are split on whether physical activity has benefits. The most positive results show modest improvement. The results are also mixed on glycemic control and there is no dose-response data. It is likely that the recommendations for Type 1 Diabetes are similar to Type 2; however, additional precautions are needed to prevent hypoglycemia during exercise and recovery.

5. What is the relationship between physical activity and microvascular complications of diabetes?

   Conclusions
   There is fair evidence to support conclusions in this area. It is very likely physical activity reduces the risk of diabetic neuropathy and likely it reduces the risks of diabetic nephropathy. It is neither likely nor unlikely to reduce diabetic retinopathy in Type 1 Diabetes and there is no data on Type 2 Diabetes.

   There is poor evidence surrounding the benefits of physical activity and the treatment of microvascular complications.

6. What is the relationship between physical activity and gestational diabetes?

   Conclusions
   There are some observational studies that suggest physical activity is beneficial in preventing gestational diabetes but there are no RCTs to support this conclusion. Overall the data suggests approximately 30 minutes per day of moderate intensity activity reduces the risk.

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