Meta-analysis show superiority of lower-carb diets in diabetes, but further studies said to be needed. Why?

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The primary problem sufferers of diabetes have is that their bodies don’t handle sugar (glucose) well. Part of the problem here is that ‘excess’ sugar in the body can attach itself to tissues, which damages them. As a result, diabetics are at an increased risk of a variety of conditions including nerve damage, blood vessel damage and kidney disease. Generally speaking, diabetes impacts on both quality and quantity of life.

As I have pointed out before, official recommendations regarding what diabetics should eat have generally focused on the need to eat a ‘low fat’ diet, and to include starchy foods (like bread, potatoes, pasta, rice and breakfast cereal) with every meal. Because these foods tend to cause brisk and substantial release of sugar into the body, and because blood sugar control is the primary underlying problem in diabetes, common sense would dictate that conventional nutritional advice for diabetics is somewhat, how shall we put it, misguided.

So, for quite some time now at least some practitioners and individuals with diabetes have been eschewing the low fat, high carb diets traditionally recommended to them. Instead, they’ve been opting for lower carb regimes. I am one of those practitioners, and my experience with carb-restricted diets is that they are generally effective for controlling blood sugar and reducing the need for medication (sometimes, it eliminates it altogether).

But those in the medical and scientific community are, I’ve found, not so interested in common sense and people’s personal experience: what they want is science. I’ve noticed generally that an approach appears to be counter to conventional ‘wisdom’, doctors and scientists generally ‘demand’ science that validates it. On the other hand, for approaches that are ‘accepted’ as beneficial, no such demands are made. Never mind that for a moment, let’s get back to the science�

I was interested to read a study published earlier this month, which assessed the effects of ‘restricted carbohydrate’ diets in the management of diabetes. This study amassed the data from 13 individuals studies, in which a lower carb diet was pitted against a higher carb diet. Actually, the lower carb diets used in these experiments ranged in carbohydrate content from 4 to 45 per cent. So, while some were genuinely low in carb, others were not.

Even so, this study found that compared to higher carb diets, lower carb regimes led to significant improvements in a number of measures, namely fasting blood glucose, levels of HBA1c (which gives an indication of blood sugar control over the last 2-3 months), and levels of unhealthy blood fats known as triglycerides. Overall, blood sugar levels fell by 15 per cent, HbA1c levels by 9.4 per cent, and triglyceride levels dropped by a third. Do bear in mind that some of diets which gave these results were not actually what some would term ‘restricted carbohydrate’.

Nevertheless, the results speak for themselves, I think. However, the authors of this study conclude that there insufficient evidence for carbohydrate restricted diets to be recommended. They also call for further research into the long term safety of such diets. If the results had been different, and the study had found that higher carb diets were superior, I wonder whether they’d be a call for further research? I think we know the answer. When it comes to changing a paradigm in medicine, it seems that not only will common sense not suffice, good science won’t do either.


Kirk JK, et al. Restricted-carbohydrate diets in patients with type 2 diabetes: a meta-analysis. Journal of the American Dietetic Association. 2008;108:91-100

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