Diabetes is a condition characterised by raised levels of sugar in the blood stream. It comes in two main forms: type 1 and type 2. Type 2 is by far the most common, and is generally related to ‘insulin resistance’ – a failure of the body to respond adequately to the blood sugar-lowering effects of insulin. While some argue for a low-fat diet for diabetics, I generally don’t. Low-carbohydrate diets are the ones that, according to the science and in keeping with common sense, usually lead to improved blood sugar control and a reduction in or complete dispensing of diabetic medication.
Activity and exercise can help blood sugar control too. Traditionally, diabetics have been encouraged to partake in ‘aerobic’ exercises such as walking, running, cycling and swimming. ‘Resistance’ exercise (e.g. weight training) is usually not promoted much for diabetics. In a recent study though, the effects of a mix of aerobic and resistance training was tested in a group of type 2 diabetics. The results, published in the Archives of Internal Medicine, were very encouraging indeed [1].
In this study, more than 600 type 2 diabetics were randomised to either exercise counselling and supervised exercise twice a week, or exercise counselling alone. The exercise sessions lasted 75 minutes each. The study lasted a year. You can download a pdf of the full article here.
Both groups became significantly more active during the course of the study, though the group undergoing supervised exercise took more format exercise than the ‘control’ group. This appeared to translate in to enhanced improvements in fitness, strength and flexibility.
Compared to the ‘control’ group (those who got exercise counselling alone), the exercise group saw significant improvements in several health markers including HbA1c levels (a measure of blood sugar control over the preceding 2-3 months), blood pressure, waist circumference, insulin sensitivity and inflammation. Essentially, taken together, these findings add up to evidence of improved health and fitness, better diabetic control and reduced risk of cardiovascular disease.
An accompanying editorial reviews the evidence regarding the effects of activity and exercise in diabetics. In particular, it makes the point that there is evidence that a combination of aerobic and resistance exercise trumps either of these forms of exercise performed alone.
One of the key pieces of evidence here is the so-called ‘DARE’ (The Diabetes Aerobic and Resistance Exercise) trial [2]. In this trial type 2 diabetics were randomised to aerobic exercise, resistance exercise or both forms of exercise, three times a week, for 22 weeks. In terms of HbA1c levels the group doing both forms of exercise did better. However, this group was also, essentially doing twice as much exercise as the other two groups. As a result, it’s difficult to discern from this evidence whether the additional benefits were down to a combination or the two forms of exercise or just increased exercise ‘volume’.
What we do have, however, is a review from last year which shows that in diabetes, resistance training can benefit blood sugar control and insulin sensitivity [3]. Whether it’s somehow ‘better’ than aerobic exercise is not clear.
My sense is that, in reality, the effect of performing both forms of exercise is going to be better for individuals than one form of exercise performed in isolation. Even if resistance exercise did not turn out to be particularly effective for diabetes management and disease risk reduction, it does increase strength. And this has huge advantages for people, in that it reduced the risk of things like falls and fractures, while at the same time helping people lead active, independent lives.
References:
1. Balducci S, et al. Effect of an Intensive Exercise Intervention Strategy on Modifiable Cardiovascular Risk Factors in Subjects With Type 2 Diabetes Mellitus: A Randomized Controlled Trial: The Italian Diabetes and Exercise Study (IDES). Archives of Internal Medicine. 2010;170(20):1794-1803
2. Sigal RJ, et al. Effects of Aerobic Training, Resistance Training, or Both on Glycemic Control in Type 2 Diabetes: A Randomized Trial. Annals of Internal Medicine. 2007;147(6):357-369
3. Gordon BA, et al. Resistance training improves metabolic health in type 2 diabetes: a systematic review. Diabetes Res Clin Pract. 2009;83(2):157-175
