Low carbohydrate diets and diabetes control

Dr Morrison, in her letter, promotes the benefit of low carbohydrate diets for people with diabetes.1 However, there is no clear consensus of evidence for this.2^,3 There is no defined low carbohydrate diet. The studies are predominantly in type 2 diabetes (a different disease and population than type 1). There is the confounding factor of weight loss, which is of established benefit in glycaemic control. Unfortunately, the studies reviewed in the articles referenced by Dr Morrison have only a short follow-up period. One review concentrates on using these diets in the short to medium term for weight loss.2 There are concerns about the possible adverse effects of these diets in terms of cardiovascular risk (dyslipidaemias), renal function, cardiomyopathy and osteoporosis.3^,4 Most of these studies have the confounding factor of increased input and support, which are likely to be of benefit to people with any chronic disease.

In the absence of conclusive evidence of benefit and lack of harm, we would propose a pragmatic solution: achieving and maintaining an appropriate weight, physical activity and a conventionally healthy balanced diet. People with type 1 diabetes can inject the insulin they lack as appropriate for the carbohydrate load and their activity level.

In our (non-expert) opinion, it is better to enable people with diabetes to live a normal life with good control than to promote a difficult-to-achieve, restrictive, expensive and potentially stigmatising diet, which has unclear long-term benefits. This is especially true for young people and adolescents.

We accept that a low carbohydrate diet may be of benefit in certain circumstances. We would welcome further research to clarify these issues in type 1 diabetes, type 2 diabetes and obesity separately. We would be happy to be proved wrong. However, there is a trade off between normal life (and quality of life) and glycaemic control. Health has wider dimensions than HbA1c.

• © British Journal of General Practice, 2006.