Can Type 2 Diabetes be prevented?
22nd January 2006
I will start with the answer to that question, yes Type 2 Diabetes can be prevented or at least delayed. Let’s start with the basics, in order to prevent any disease you first have to find what is causing that disease. Right now we have enough evidence about the causes of type 2 diabetes and we can safely pinpoint a number of factors that are responsible for it. Some of these factors include age, gender, race, ethnicity, family history of diabetes, overweight/obesity, high fat diet, high consumption of refined carbohydrates, fetal nutrition and physical inactivity. Just by looking at those factors we can easily divide them in two categories, the ones that can be modified and the ones that cannot be modified. From the ones that can be modified, obesity seems to be the most important of all since it has been estimated that obesity is associated with about 80-90% of all the cases of type 2 diabetes mellitus (Astrup & Finer, 2000).
It should also be noted that type 2 diabetes is the result of abnormalities in insulin action and insulin secretion. Individuals progress gradually from normal glucose tolerance to impaired glucose tolerance and finally to diabetes. Approximately 40% of subjects with impaired glucose tolerance progress to diabetes after 5-10 years (Zimmet et al., 2001) and additionally this transition has been associated with an increase in body weight (Weyer et al., 1999). This fact gives health care professional a potential window of opportunity to intervene so that they can prevent the final outcome of diabetes. Furthermore, it should be noted that although diabetes is a treatable disease it’s not curable, a fact that makes diabetes prevention a very attractive prospect both for health and financial reasons.
So, what will happen if we modify some of the risks factors associated with type 2 Diabetes like obesity, physical inactivity, fetal nutrition and diet in general? The easy answer would be that the risk of developing type 2 diabetes would decrease. However without any research to back up that statement we would just be speculating. Thankfully, there are enough experimental data to support the statement that the risk of type 2 diabetes decreases and therefore can be prevented if we act towards modifying mostly the lifestyle risk factors that are associated with the development of type 2 diabetes.
The larger randomized controlled clinical trial conducted in this field of study is by far the Diabetes Prevention Program in the USA with a sample of 3234 subjects at high risk of developing type 2 diabetes. The participants were randomized to one of three groups, which were: standard lifestyle recommendations plus metformin at a dose of 850mg twice daily, standard lifestyle recommendations plus placebo and an intensive program of lifestyle modification. The goals of the latter group was weight reduction of at least 7% of initial body weight through a healthy low calorie, low fat diet and increase of moderate physical activity at 150 min per week (The Diabetes Prevention Program Research Group, 2002)
After an average follow-up of 2.8 years a relative reduction of 58% in the progression to type 2 diabetes for the lifestyle group compared to the placebo group was reported. The reduction for the metformin group was 31% as compared with the placebo group. Finally diabetes incidence was 39% lower in the lifestyle group compared with the metformin group (Knowler et al., 2002). The greater reduction in the lifestyle intervention group can be attributed to the greater weight loss and the higher physical activity levels that were achieved by this group compared to the other two . It should be noted that this fascinating results for the lifestyle intervention group where achieved even though only 50% of the group managed to achieve the goal of 7% of weight loss (at 24 weeks) while 74% achieved the goal of 150min of moderate physical activity per week (Knowler et al., 2002). These facts indicate that even very modest changes in lifestyle can have very good results decreasing the risk of type 2 diabetes mellitus.
Another interesting study is the Finnish diabetes prevention study (DPS) which was a multicenter randomized controlled trial. The recruitment of the subjects started in 1993 and finally 522 subjects at high risk of developing type 2 diabetes were recruited for the study and randomized in two groups. The two groups included a control group and an intensive diet and exercise intervention group. The control group received only general advice at the start of the trial and at each yearly visit, while the intervention group subjects received frequent individualized advice and also group sessions. The study had five main goals, which were 5% weight reduction, fat consumption less than 30% of the total energy, saturated fat consumption less than 10%, fiber consumption of at least 15gr per day and physical activity at least for half an hour per day (Eriksson et al., 1999).
After two years the mean weight loss in the intervention group was statistically higher than the control group (3.5 vs 0.8kgr p<0.001). In addition to that the absolute danger for diabetes was 32 cases per 1000 person years in the intervention group compared with 78 cases per 1000 person years in the control group. After 3.2 years of average follow-up the risk of developing diabetes was reduced by 58% in the intervention group compared with the control group. It should also be noted that from both groups none of the subjects that managed to accomplish four or more of the targets progressed to diabetes (Tuomilehto et al., 2001).
What I keep from all these, is that moderate weight loss and moderate lifestyle changes can help in the prevention of type 2 diabetes. It may sound simple but it is extremely important.