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

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

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

  1. Norah Ethel Coleman 11 January 2008 at 1:50 pm #

    Dear Dr. John:
    I absolutely agree with low-carb. Six years ago, when I devoloped Type 2 diabetes – which runs on both sides of the family – the endocrinologist said: “The only thing you can’t eat is sugar”. When I pointed out that there is such a thing as glicemic index, he said: “Bah, bah, bah. Don’t believe in that nonsense.” At first I decided to follow his advice, since pasta, rice and potatoes are cheaper than protein foods and fill up the family at dinner time. After my daughters left home I made a thorough research of my own, since I had attended an American school which taught nutrition in the 60s, so I knew where to start off. Well, I reached the same conclusion, adopted this low-carb diet, lost several kilos unnecessary weight – which the endocrinologist was always pecking on me about – and have almost said good by to the pills. I really beleive white “poisons” are a kick to the pancreas and nowadays feel much better and more confident about this condition. Thanks for your support and I thoroughly enjoy your newsletter. Keep up the good work.

  2. Janet Alton MNIMH 12 January 2008 at 9:13 pm #

    I find it staggering that “safety” of low carb diets is ever an issue given the eons of time of human evolution when we must have eaten low carb diets, long before grains were farmed and turned into bread and pasta etc. You might argue, on this principle, that it may not be “safe” to eat a high-carb diet! (Which appears to be the case)

  3. helen 13 January 2008 at 9:18 pm #

    (Janet) the whole scare campaign against low carb (which some idiots still try calling NO carb – although those diets do exist too) is just part of the manipulation of the masses by those with vested interests in the “business of illness”. Keep a steady stream of ill people calmouring for drugs which will not “cure” them but will make all those whose incomes rely on a huge sick population of people to keep their profits rolling in. It really is a no brainer sick people make money, why would it benefit anyone making money on their illnesses to want them healthy?? Just think of all the lovely “research” dollars that would dry up for world wide diabetes associations, heart & cancer associations if the numbers of people with these “illnesses” realised it was what they were eating & not just bad luck or bad genes that caused their problems. If eating low carb even cut the illness ratio in half they would lose billions of dollars, in what universe would you find anyone willing to give up that sort of money, just to see people healthy? No wonder they try to protray low carb as not safe & put out a great deal of misinformation & just plain lies about this way of eating.

  4. Jackie Bushell 18 January 2008 at 5:32 pm #

    Once again, Dr Briffa has hit the nail on the head.

    One day, those who don’t understand low carb or don’t want to understand it will be unable to avoid it … Keep up the good work Dr Briffa in making that day come sooner.

  5. isobel 10 February 2008 at 6:03 pm #

    I couldn’t agree more – my father has had diabetes type II ( a problem which runs in his side of the family) for nearly 50 years and has controlled it with a low carb diet (this was the advice given to diabetics in the early 60s) he has never taken insulin. His Dr is always amazed at how well his diabetes is controlled for his age.One of my sisters was also diagnosed with diabetes a couple of years ago and has basically adopted the same diet (despite being given the “low fat diet”advice) and has also had no problems in controlling her insulin levels.

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