Regular Exercise Cuts Type-2 Diabetes Risk

Regular physical exercise can lead to massive reductions in type-2 diabetes risk according to a number of scientific studies.

One of the largest studies on the impact of exercise on type-2 diabetes risk was conducted in 1992 by researchers from the Department of Medicine at the Harvard Medical School in Boston, USA. The researchers used data from the Physicians’ Health Study which involved 21,2171 male physicians from the United States aged between 40 and 84 who were followed for five years.

Over the course of the study, 285 of the participants were diagnosed with type-2 diabetes. The researchers found that those who exercised more than once a week were 36% less likely to develop type-2 diabetes than those who exercised less than once a week. Furthermore, the incidence of type-2 diabetes continued to decrease with increasing levels of exercise. Compared to those who exercised less than once a week, there was a 23% reduction in type-2 diabetes in those who exercised one to two times a week, a 38% reduction for those exercising between two and four times a week, and a 42% reduction for those who exercised at least five times each week.

The study appears in the appears in the July 1, 1992 issue of The Journal of the American Medical Association.

Exercise also appears to be particularly effective in preventing the progression of pre-diabetes into full diabetes. A 1997 study published in the journal Diabetes Care looked at whether dietary and/or exercise intervention could halt the progression from impaired glucose tolerance (IGT) to diabetes. Impaired glucose tolerance is a form of pre-diabetes where an individual has a two-hour blood glucose level between 140 to 199 mg per dL following an oral glucose tolerance test.

The study consisted of 577 Chinese men and women with impaired glucose tolerance who were randomized to receive either diet intervention, exercise intervention, both diet and exercise intervention, or nothing. The exercise intervention was aimed at increasing exercise levels by 1 unit a day (2 units in younger individuals without heart disease). A unit of exercise was defined as 30 minutes of mild activity or 10 minutes of strenuous activity.
Progression of impaired glucose tolerance to diabetes

The researchers found significant reductions in the progression of impaired glucose tolerance to diabetes in each of the intervention groups. After 6 years of follow-up, 67.7% of the control group had developed diabetes compared to 41.1% in the exercise group, 43.8% in the diet group, and 46% in the diet & exercise group. Exercise was particularly effective in lean individuals (those with BMI < 25 at the beginning of the study) with the risk of developing diabetes dropping by more than half compared to the control group.

Several mechanisms are responsible for the beneficial effects of exercise on diabetes risk. First, regular exercise leads to reductions in body weight through body fat loss. High body levels of body fat, especially around the abdominal area, is an established risk factor for type-2 diabetes. This is because abdominal fat secretes hormones known as adipokines that can impair glucose tolerance.

In addition to this, sustained physical activity leads to improvements in insulin sensitivity meaning the body needs less insulin in order to control blood sugar levels. Strenuous exercise also increases glucose uptake into the skeletal muscles, particularly after meal times. This can help reduce the rapid blood sugar spikes that often occur after meals in those with either pre-diabetes or diabetes.