Author: Kirstie Lamb, MMedSci – Researcher and Trainer in Public Health/28 March 2018
Diabetes UK evidence-based nutrition guidelines were first published in 1982, with several updates and revisions to these having been made since. The most recent previous update took place in 2011. At this year’s Diabetes UK Professional Conference in London, 14th-16th March 2018, the latest update to guidelines was officially launched. The main aim of these guidelines is to provide evidence-based nutrition recommendations to healthcare professionals supporting adults with or at risk of diabetes (both Type 2 and Type 1). Whilst the guidelines cover numerous other considerations including pregnancy, food supplements, sweeteners and complications, this blog will focus on the core nutritional messages for those with, or at risk of, Type 2 diabetes.
In order to generate these guidelines, a committee of diabetes specialist dieticians reviewed relevant studies published up to July 2017 (an exception was made to allow the inclusion of the DiRECT Study, discussed in one of our previous blogs, which successfully demonstrated remission of Type 2 diabetes through dietary changes). Recommendations were graded based on the strength and quality of supporting evidence.
One of the most notable changes from previous guidelines is the shift in focus towards foods rather than nutrients. It has been acknowledged that the optimal proportion of macronutrients (i.e. how much carbohydrate, protein and fat we should consume) is not clear, but that the overall diet quality and subsequent impact on weight is important. Nutrition management is an integral part of education and clinical care. The guidelines state that advice should be tailored to individuals and acknowledge that food choices need to be acceptable and enjoyable whilst helping to achieve health goals (e.g. improved glycaemic control, weight, lipid profile and/or blood pressure).
This is very much consistent with X-PERT’s philosophy that ‘one size does not fit all’ and that dietary changes should not be prescriptive. The degree of adherence to a dietary approach has arguably the biggest influence on outcomes (both short-term and long-term), so we encourage you to experiment and find out which approach and lifestyle changes work for you, allow you to meet your health goals, and that you enjoy!
The guidelines also identify certain foods that are associated with an increased risk of Type 2 diabetes and therefore recommend restricted consumption of these. These foods include:
* red and processed meat
* potatoes (particularly French fries)
* sugar-sweetened beverages
* refined carbs (e.g. white bread and white rice).
In contrast, there are several foods associated with reduced risk which are encouraged, including:
* some fruit
* green leafy vegetables
* tea and coffee.
Several dietary patterns are also highlighted as being associated with a reduced risk of Type 2 diabetes and poor glycaemic control. These patterns include:
* Mediterranean – defined as being ‘higher in foods rich in mono-unsaturated fats, vegetables, fruits, wholegrains, nuts, fish and legumes; moderate alcohol; and lower in red and processed meat, sugary foods, refined carbohydrates and processed foods’
* DASH (Dietary Approaches to Stop Hypertension) –this is an eating pattern designed to reduce/prevent high blood pressure and is defined as being ‘higher in foods rich in potassium, calcium and magnesium…and lower in saturated fat, sodium, meats, sweets and sugar-sweetened beverages’
* Vegetarian and vegan
* Nordic – this is very similar to the Mediterranean diet. It is defined as being ‘based on traditional healthy Nordic foods’. These include fruit, vegetables, berries, wholegrains, fish and rapeseed oil and restrict foods high in salt, added sugars and saturated fat
* Moderate carbohydrate restriction
Reduced carbohydrate and Mediterranean dietary approaches in particular are supported throughout our programmes. The guidelines recognise that low-carb diets can be both safe and effective; although they currently only support this in the short-term, stating that ‘long-term effects are currently unknown’. Several long-term low carbohydrate studies have been undertaken though, displaying beneficial effects of this dietary approach[1, 2].
The overall advice from the guidelines is for most individuals to aim for a Mediterranean style diet or equivalent healthy eating pattern. However, as they also suggest that evidence is limited for the superiority of a single dietary approach in long-term management of hyperglycaemia (and thus a range of diets may be suitable), dietary choice should ultimately be based on nutritional quality, personal preference and acceptability.
The guidelines acknowledge that there is no optimal amount of carbohydrate. However, it is advised that individuals with Type 2 diabetes are offered individualised education to support them in identifying and quantifying their dietary carbohydrate intake. These individuals are encouraged to choose low GI foods and to consider reducing the total amount of carbohydrate consumed, something we fully support during our X-PERT programmes. In addition to the quantity of carbohydrate, they acknowledge that the quality of carbohydrates is also important. For example, refined carbohydrates and potatoes are identified as foods that increase the risk of Type 2 diabetes. Increased fibre is also encouraged; this can help with glycaemic control and may offer additional health benefits through its positive impact on the gut microbiota.
The guidelines conclude that as the evidence for restricting saturated fat is mixed they are sticking with their previous guidance to restrict its intake; with no consideration of the food source or type of saturated fat. This is surprising, as the guidelines also encourage the consumption of dairy for reducing risk, which is often high in saturated fat. Additionally, the differential effect of saturated fats was acknowledged by members of the panel at the Diabetes UK ‘launch’. This may seem contradictory and confusing to those following the guidelines Therefore, greater recognition of the different types of saturated fat and their varying impacts on health is necessary in future updates of the guidelines.
In line with recommendations for the general population, reductions in the intake of trans-fatty acids are encouraged; however, it is also stated that trans-fatty acids in dairy products do not need to be discouraged, again promoting these foods.
Individuals with Type 2 diabetes who are either overweight or obese are encouraged to aim for a weight loss of 15kg in order to achieve remission, and at least 5% weight loss for improved glycaemic control (including HbA1c and insulin sensitivity) and reduced cardiovascular disease risk (including total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides and blood pressure). Similarly, high risk groups are advised to aim for weight loss of at least 5%, where appropriate, to reduce their risk of Type 2 diabetes.
Unfortunately, there still seems to be an emphasis on the importance of total energy intake. For example, weight loss aims for overweight/obese individuals with Type 2 diabetes are instructed to be achieved by reducing calorie intake and increasing energy expenditure, i.e. ‘eat less, move more’. This focus on calories alone could be interpreted as being contradictory to their ‘one size does not fit all’ message and their statement that diet quality is more important for good health.
Overall, these guidelines are very positive and a step in the right direction to accepting that different dietary approaches, including low-carb and Mediterranean, can be beneficial to health! However, there are still several areas where improvements could be made, most notably the guidance around the different types of fats.
- Tay, J., et al., Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial.Am J Clin Nutr, 2015. 102: p. 780–90.
- Hallberg, S.J., et al., Effectiveness and Safety of a Novel Care Model for the Management of Type 2 Diabetes at 1 Year: An Open-Label, Non-Randomized, Controlled Study.Diabetes Therapy, 2018.