Lower carbohydrate diets for adults with type 2 diabetes.

Mamta Singh,Darren C Greenwood,Ian S Young,Nita G Forouhi,Peter J Aggett,Estella S Hung,Rachel E Allen,Douglas Twenefour,Adrienne Cullum,Rachel Pryke,Roy Taylor,Pamela Dyson,Ruth Waxman

doi:10.1111/dme.14674

Abstract

In May 2021, the Scientific Advisory Committee on Nutrition (SACN) published a risk assessment on lower carbohydrate diets for adults with type 2 diabetes (T2D)(1). The purpose of the report was to review the evidence on 'low'-carbohydrate diets compared with the current UK government advice on carbohydrate intake for adults with T2D. However, since there is no agreed and widely utilised definition of a 'low'-carbohydrate diet, comparisons in the report were between lower and higher carbohydrate diets. SACN's remit is to assess the risks and benefits of nutrients, dietary patterns, food or food components for health by evaluating scientific evidence and to make dietary recommendations for the UK based on its assessment(2). SACN has a public health focus and only considers evidence in healthy populations unless specifically requested to do otherwise. Since the Committee does not usually make recommendations relating to clinical conditions, a joint working group (WG) was established in 2017 to consider this issue. The WG comprised members of SACN and members nominated by Diabetes UK, the British Dietetic Association, Royal College of Physicians and Royal College of General Practitioners. Representatives from NHS England and NHS Health Improvement, the National Institute for Health and Care Excellence and devolved health departments were also invited to observe the WG. The WG was jointly chaired by SACN and Diabetes UK.

Highlights

The terms of reference for the working group were to review the evidence on lower carbohydrate diets compared with the current government advice for adults with type 2 diabetes (T2D); consider the impact, in adults with T2D, of lower compared with higher carbohydrate diets on markers and clinical outcomes of T2D including any potential adverse effects and make recommendations based on the review of the evidence
The overall quality of the evidence base was limited by a number of uncertainties in the data, including variability in the definition of a low-carbohydrate diet; smaller than prescribed differences in reported carbohydrate intakes between lower and higher carbohydrate diets; inherent inaccuracies in estimates of self-reported dietary intakes and lack of information on adherence to prescribed diets
An important limitation was that the risk of bias was high or unclear in most of the primary randomised controlled trials (RCT) that was included in the MA

Summary

| BACKGROUND

The terms of reference for the working group were to review the evidence on lower carbohydrate diets (alongside higher fat and/or higher protein) compared with the current government advice for adults with type 2 diabetes (T2D); consider the impact, in adults with T2D, of lower compared with higher carbohydrate diets on markers and clinical outcomes of T2D including any potential adverse effects and make recommendations based on the review of the evidence. In England, the National Institute for Health and Care Excellence has issued guidelines for the identification, diagnosis and management of T2D including dietary advice that is in line with UK government advice for the general population.[9] The Scottish Intercollegiate Guidelines Network has issued guidelines on the management of diabetes including offering adults with T2D a range of dietary options for achieving weight loss that may improve glycaemic control.[10]. The aim of reducing energy intake is weight loss, which in turn improves glycaemic control. Glycaemic index and glycaemic load are measures of the post-prandial blood glucose response to foods Both Diabetes UK and the American Diabetes Association emphasise tailoring advice to the individual, and both note the lack of clear evidence for a specific dietary intake of carbohydrate for those with T2D.11,12. SACN initiated this evidence review in response to a request from Public Health England, for a systematic assessment of the scientific evidence on ‘low’-carbohydrate diets, in recognition that such diets are gaining attention and increasingly being promoted

| METHODS

Findings

| Conclusions