Preventing Type 2 Diabetes: Going Beyond the Obesity Discussion
The standard approach to discussion of Type 2 diabetes is centred, rightly so, on obesity, waist size and level of activity. This is because of the proven link between obesity and increased insulin resistance; as well as the benefits of exercise on muscle utilisation of glucose and responsiveness to insulin. (See NHS link for Type 2 Diabetes here for more details.)
The main treatments for Type 2 Diabetes are similarly focused on improving insulin effectiveness, modulating the actions or secretion of insulin or glucagon (hormones that regulate glucose levels), or improving glucose utilisation by body cells. While discussions around diet are often incorporated into the lifestyle management and prevention of the condition, this is mainly from the viewpoint of reduced calorie intake, improved dietary fibre (both to improve stable background glucose levels and reduce hunger pangs) and ensuring regularity in consumption of healthy main meals (in order to reduce the likelihood of snacking).
It is therefore refreshing that two studies published this past week in the British Medical Journal have both solidified existing knowledge and added a new dimension to the understanding of the prevention of Type 2 Diabetes.
The first one, by Zheng et al, has shown an independent link between the level of Vitamin C, or carotenoids, and the incidence of Type 2 Diabetes. Carried out in Europe and involving analysis of thousands of patient records, it shows that higher plasma levels of Vitamin C and carotenoids are positively associated with reduced incidence of Type 2 Diabetes. In other words, the more fruit and vegetables you eat regularly, the lower your chances of getting Type 2 diabetes.
In standard research fashion, we need to mention that the authors acknowledge a number of possible limiting and confounding factors. For instance, the study was carried out in Europe and involved predominantly white patients. Similar studies might need to be carried out in other racial groups to confirm applicability to these groups. Secondly, as the analysis involved a review of patient data, but not patients themselves, it is possible that those patients with higher Vitamin C and Carotenoid levels were already engaged in healthier lifestyle habits in the first place, and thus were less likely to develop Type 2 diabetes. We also need to mention that the authors do not present a hypothesis on the mechanism by which Vitamin C or Carotenoids might actually influence the development of Type 2 Diabetes. This is something that needs further exploration.
However, despite these potential limitations, we are of the view that the overall study design is very good and agree with the conclusions of the authors:
This study suggests that even a modest increase in fruit and vegetable intake could help to prevent type 2 diabetes, indicated by objective biomarkers of consumption, regardless of whether the increase is among people with initially low or high intakeZheng et al
The second study, also published in the BMJ, explored the link between the intake of whole grain foods and the development of Type 2 diabetes. This is based on the well-known (in healthcare academic settings) Nurses’ Health and Healthcare Professionals Follow-Up studies in the USA. Perhaps not surprisingly, the authors came to the following conclusion:
Higher consumption of total whole grains and several commonly eaten whole grain foods, including whole grain breakfast cereal, oatmeal, dark bread, brown rice, added bran, and wheat germ, was significantly associated with a lower risk of type 2 diabetes. These findings provide further support for the current recommendations of increasing whole grain consumption as part of a healthy diet for the prevention of type 2 diabetes.Yang Hu et al
We say this is not surprising because we would expect that whole grain foods promote the moderated release of glucose into the blood stream, while enhancing the sensation of being “full”, thus reducing the likelihood of feeling hungry and the propensity for intake of snacks. This would also be expected to have a beneficial effect on weight management. We also think that these effects could have contributed to the positive effects seen with Vitamin C and Carotenoids in the first study referred to above.
And so, it appears that we can identify several factors as influencing the development of Type 2 Diabetes. The infographic below summarises the factors outlined above.
This should hopefully positively influence clinical and lifestyle guidance given to patients, leading to improved health outcomes overall and a reduction in the incidence of Type 2 Diabetes.