Type 2 diabetes: prevention can be a few steps away

More than a million people will be diagnosed with type 2 diabetes this year. The overwhelming majority will be overweight adults - a group slow to change their eating and exercise habits in spite of the potentially dire consequences of the disease. But a new study in The New England Journal of Medicine reports that even small changes in diet and activity level can considerably reduce a person's chances of developing this form of diabetes.

The proof is in the eating and exercise

Finnish researchers randomized 522 middle-aged, overweight men and women with impaired glucose tolerance to one of two groups. The intervention group received intensive diet and exercise training, with the goals of reducing body weight by 5%; reducing total fat to 30% and saturated fat to 10% of calorie intake; increasing fiber intake to 15 grams per 1000 kcal; and exercising at least 30 minutes each day. The control group received only printed information on diet and exercise. Researchers assessed weight and blood glucose levels several times during the study.

At the end of one year, those in the intervention group lost an average 4.2 kg, compared with an average weight loss of 0.8 kg of those in the control group. Progress was not as pronounced during the second year of the study, but those receiving diet counseling still managed to weigh in at an average 3.5 kg less than their starting weight, while those in the control group stayed the same.

The intervention group also showed a significant reduction in waist circumference and fasting plasma glucose concentration, as well as in plasma glucose and serum insulin concentrations two hours after an oral glucose challenge.

Small changes made a big difference

Four years into the study, the cumulative incidence of diabetes was 11% in the intervention group and 23% in the control group. Using regression analysis, the researchers estimate that the diet and exercise changes made by those in the intervention group reduced their risk of type 2 diabetes by 58%.

Those in the intervention group who exercised at least 4 hours per week, even if they were not able to meet the weight loss goal, fared better during the first year of the study than those who stayed sedentary (Odds Ratio = 0.2, 95% CI 0.1-0.6). Any kind of moderate exercise - walking, weight training, yard work - counted toward the exercise goal, an encouraging note to sedentary adults who may be hesitant to join an organized exercise program.

Predictably, those who were most successful in meeting both their diet and exercise goals were the ones most likely to see substantial health benefits. During the course of the study, diabetes did not develop in any participant, regardless of treatment group, who met at least 4 of the 5 diet and exercise goals. On the other hand, 38% of those in the intervention group and 31% of those in the control group who met none of the study's goals developed diabetes within 4 years.

The authors acknowledge that it can be hard to get even high-risk patients to change eating and exercise habits, and that success is usually measured in small increments. But, for those "on the bubble" for type 2 diabetes - overweight, sedentary, middle-aged adults with impaired glucose tolerance - this study suggests that even small changes for the better can have a significant effect on their health.