Low-carbohydrate diet proven to be very effective in type 1 diabetics (just as you’d expect)

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A fundamental problem with diabetes is the usually-elevated levels of blood sugar (glucose) that go with it. These glucose molecules can react with proteins in the body, damaging them. This process – known as ‘glycation’ – is at the heart of diabetic complications such as cataracts, nerve damage, kidney disease and circulatory problems.

There is also some evidence that high blood glucose levels can impair the uptake of cholesterol into the brain. And while many have done their level best to convince us that cholesterol kills people, it actually performs vital functions in the body and brain.

For example, cholesterol is required in the brain as an antioxidant, an electrical insulator (in order to prevent ion leakage), as a structural scaffold for the ‘neural network’, and a functional component of all membranes. Cholesterol is also utilized in the wrapping and synaptic delivery of brain chemicals (neurotransmitters), and also plays an important role in the formation and functioning of the ‘synapses’ (the tiny gaps between nerve cells that regulate cell-to-cell communication. You can read more about this and the potentially damaging effect glucose has on the brain here.

I was interested to read about a recent study in which the relationship between diabetes/blood sugar control and mental functioning was assessed in adults over a 9-year period [1]. Basically, mental functioning was best in people without diabetes, and worst in people who were diabetic at the start of the study. Those who developed diabetes during the study were, overall, somewhere in between. Also, it was found that poorer control of blood sugar levels led to worse outcomes.

Now, this is an epidemiological study, which means we cannot be assured that diabetes and worsened blood sugar control and diabetes cause ‘cognitive decline’. However, we do also have a plausible mechanism (see above) which might account for this association.

So, what options exist for individuals seeking to control blood sugar levels? One approach might beto avoid eating foods tat disrupt blood sugar levels, including the ‘wholesome wholegrains’ and ‘essential starches’ some health professionals and health agencies insist diabetics should eat. You can read more about this (in my view) nonsense advice here.

One of the arguments that some use to justify the presence of grains and other starches in the diet of diabetics, is that we ‘need’ these foods for blood sugar regulation. Actually we don’t. Plus, it also stands to reason of course that that less we eat of sugar-disruptive foods, the less insulin will be required, and the better blood sugar control will be.

Most diabetics have what is termed ‘type 2 diabetes’ which is usually caused by insulin not working as it should. Some type 2 diabetics take insulin to control their condition, but most do not. In the case of type 1 diabetes, insufficient insulin is being secreted, and these individuals must take insulin to keep blood sugar levels from running out of control. Insulin lowers blood sugar, so it’s often said that starchy carbohydrate is particularly important to type 1 diabetics to ‘balance’ the insulin they’re injecting. But how about this: if a type 1 diabetic eats less carb, they will require less insulin.

So now we have the potential for good blood sugar control and lower insulin requirements. And, as has been noted, this approach is likely to help prevent highs and lows in blood sugar which are common in type 1 diabetic who base their diet on starchy carbs.

In my experience, when one discusses this approach and the logic to it with a type 1 diabetic, they get it in an instant. I’ve met many type 1 diabetics who have worked this out for themselves. And yet, many health professionals and the charity Diabetes UK remain intransigent.

For what it’s worth, some Swedish researchers recently published a study in which a low carbohydrate diet was tested in a group of type 1 diabetics [2]. The study subjects were asked to limit their carbohydrate intake to no more than 75 grams a day. Blood sugar control was assessed with a test known as the HbA1c, which provides a measure of overall control in the preceding three months or so. The HbA1c is usually expressed as a percentage, with less than 5 per cent generally being taken to show very good blood sugar control (typically seen in non-diabetics). The average HbA1c in the study subjects was 7.6 at the start of the study. The HbA1c was retested at 3 months and 4 years.

As with all things, some stuck with the advice regarding carbohydrate restriction, and some did not. Those who did not comply with the advice saw no significant change in their HbA1c levels over time. On the other hand, the subjects who went with the advice saw their HbA1c levels drop to an average of 6.0 per cent. Clinically, this would be seen as a very significant drop clinically, and signal generally much improved blood sugar control.

The authors make the point that individuals adjusted their insulin downwards as carbohydrate was restricted. So, what we have is much better blood sugar control, lower risk of complications, and less need for medication by adopting a lower-carbohydrate diet.

This is a great study, I think, and the reason I use the words ‘for what it’s worth’ above is because the results are exactly what practitioners with experience of this approach in clinical practice and what individuals who have tried this approach for themselves would expect. But at least now, we have a nice, long-term study proving the value of carbohydrate restriction in type 1 diabetes. And the level of restriction was not even ‘extreme’. Feel free, if appropriate, to introduce your health care provider to this evidence. Their response to it might tell you a lot about their capacity to think for themselves.

Diabetics should discuss any contemplated changes to their diet and medication regime with their doctor first.


1. Yaffe K, et al. Diabetes, Glucose Control, and 9-Year Cognitive Decline Among Non-Demented Older Adults Without Dementia. Archives of Neurology, June 18, 2012

2. Nielsen JV, et al. Low carbohydrate diet in type 1 diabetes, long-term improvement and adherence: a clinical audit. Diabetology and Metabolic Syndrome 2012;4:23

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