Dr Trudi Deakin: 2018 Diabetes UK guidelines – a step in the right direction?
Dr Trudi Deakin obtained her degree in nutrition and dietetics in 1993, a teaching qualification in 1998 and a doctorate in diabetes in 2004. She worked as a dietician in the NHS until 2008, when she left to set up the registered charity, X-PERT Health, which delivers structured education for both healthcare professionals and the public. She also sat on the committee for the 2011 Diabetes UK guidelines. Through her programs, Dr Deakin has trained over 1000 healthcare professionals as educators, which has led to the education of over 250,000 people struggling with their weight or diabetes. This talk was given at the Public Health Collaboration conference 2018 at the Royal College of General Practitioners in London.
Dr Deakin starts by outlining what, in a perfect world, constitutes good evidence and highlights some of the issues with the reliability of nutrition literature. These include the inability of observational studies to infer causation, limitations of food frequency questionnaires and conflicts of interest impacting study outcomes. Dr Deakin also explains that the risk factors for a disease may not accurately reflect the root cause of it.
Regarding the new 2018 Diabetes UK guidelines, Dr Deakin highlights their admission that there’s no one-size-fits-all approach and their support of individualised approaches as positive points. She also notes that the image on the front cover of the guidelines is a spread of real, unprocessed food – although there is actually no mention of real food in the guidelines themselves. Dr Deakin also has a couple of criticisms, noting that the new guidelines have been built from the 2011 ones (which she opines contained errors) and also that the recruitment process for the panel’s dieticians was suboptimal.
Dr Deakin was on the committee for the 2011 Diabetes UK guidelines and raised concerns back then, that there was no robust search strategy or literature review (with some recommendations backed by only one reference) as part of the process. She says her concerns were ignored and she had not been invited to back to the panel for the 2018 guidelines. However, Dr Deakin notes that the search strategy for the 2018 guidelines is markedly better than before, with the caveat that they are still emphasising cardiovascular risk instead of cardiovascular events and mortality. There was also a grading system for assessing the quality of evidence, however Dr Deakin expresses doubts over the accuracy of this.
Though the new guidelines make recommendations on preventing type 2 diabetes, one important thing that is very much left out is a consideration of the root cause (aetiology) of the disease. The underlying cause of type 2 diabetes, Dr Deakin explains, is a gradual rise in insulin levels leading to insulin resistance. It stands to reason then, that this knowledge would be important in prevention. Instead, there are a number of dietary recommendations that were included in the guidelines such as lower fat and saturated fat intakes. However, looking at the source studies for these recommendations, Dr Deakin explains that these goals were not adhered to and so cannot be said to be responsible for any positive outcomes. To reiterate the importance of insulin, Dr Deakin explains that fat stores are effectively locked away when insulin levels are high, preventing them from being burned. She suggests that the guidelines might be better off focusing on addressing the metabolic syndrome criteria, rather than simply recommending 5% weight loss.
The Diabetes UK guidelines list a number of diets that they say can reduce the risk of type 2 diabetes. Dr Deakin agrees that the evidence for the Mediterranean diet is strong and robust, but opines that the evidence presented for the others (DASH, vegetarian, vegan and Nordic diets) does not hold up as well. She also notes that the ‘moderate carbohydrate restriction’ listed by the guidelines as a preventative diet should instead be called a ‘low carb diet’, given that it was based on a carb intake of 115 grams per day. Dr Deakin highlights that there may have been a bias against low carb diets in the guidelines, as certain phrases present in their references that favour low carb diets were omitted. In addition, a systematic review that found Atkins and Paleo diets to be more effective than lower fat diets for weight loss was not included in the literature search. All that said, the new guidelines are a step in the right direction, as they allow for increased flexibility in dietary approaches.
Dr Deakin again reiterates that she feels the guidelines place too much emphasis is placed on weight loss, rather than metabolic control, for preventing type 2 diabetes. For example, the guidelines recommend a 15kg weight loss goal after type 2 diabetes diagnosis, but do not mention the role of liver and pancreatic fat. While the guidelines state that different approaches can be effective, Dr Deakin notes that low carb and Mediterranean diets in particular were effective for decreasing weight and HbA1c.
Dr Deakin outlines a few improvements she would make to the Diabetes UK guidelines and to the processes that created them. She opines that education should be available to support people with carbohydrate restriction, which leads her onto what she says is the best part of the guidelines:
The guidelines do mention limitations of the evidence for low carb interventions, however as Dr Deakin explains, these supposed limitations do not seem to hold true when looking at the literature. For instance, low carb interventions are said to have high drop-out rates, when in fact, the drop-out rates for the low fat interventions are higher.
To round off the talk, Dr Deakin presents the holes in the evidence used by Diabetes UK to recommend replacing saturated fat with unsaturated fat in the guidelines. Overall, she says, the new Diabetes UK guidelines are certainly a step in the right direction and contain many positives. She summarises her ideal guidelines as eating real food, with carbohydrate to tolerance, moderate protein and healthy fats to fullness.