By Leah Avery, Teesside University, UK.
Type 2 diabetes was previously considered a progressive condition, with an inevitable need for insulin therapy, however lifestyle behavioural change research challenges this pessimistic prognosis. As prevalence of type 2 diabetes continues to increase, so does evidence supporting the important role of the food and changing what we eat to successfully manage the condition.
Dietary approaches can largely be divided into two. Those that focus on what we eat (e.g., carbohydrates) to optimise metabolism and glycaemic control via slow and steady weight loss. Others that focus on the amount eaten, such as the low-calorie diet involving significant energy restriction for rapid weight loss.
- The low-carbohydrate diet
It was previously recommended that people with type 2 diabetes maintain a diet low in sugar with lots of carbohydrate rich foods because it was believed that these foods released sugar into the blood gradually. We now know that many foods rich in carbohydrate release sugar into the blood more quickly than sugary foods. Despite this, the low-sugar/high carbohydrate approach is still followed by many people with type 2 diabetes, and this approach can prevent good glycaemic control and should be avoided.
Current evidence indicates a need to support people with type 2 diabetes to reduce their carbohydrates by making alternative food choices. This involves learning about which foods are high in carbohydrates, and measuring personal intake of carbohydrate over time (this practical strategy is referred to as self-monitoring). The patient should then be supported to reduce their intake of carbohydrates by setting goals and making action plans (the when, where, and how they will reduce high-carb foods) and coping plans (if I encounter any obstacles, then I will do something) to overcome any barriers (e.g., carbohydrate-rich snack temptation at work) to eating fewer high carbohydrate foods. Evidence supporting a reduction in carbohydrates to successfully manage type 2 diabetes by promoting weight loss has increased, with low carbohydrate approaches leading to better outcomes than moderate carbohydrate diets.
However, each patient is unique which represents a challenge for finding the optimal carbohydrate intake and associated food choices. For example, individuals have their own personal carbohydrate tolerance level, i.e., how much carbohydrate they can eat before it impacts negatively on their weight and glycaemic control. Personal fat threshold works in a similar way, i.e., some people with type 2 diabetes need to lose a lot of weight to successfully manage their glycaemic levels, while others can achieve glycaemic control with less weight loss. Furthermore, some people develop type 2 diabetes at a much lower Body Mass Index than others and personal fat threshold can partially explain why. Where a patient stores their fat (i.e., predominantly in and around their organs or around the outer edges of their body), and their personal thresholds can help to explain some of the differences in response to diets. It can also help to explain why diets work for some and not others. It is useful to communicate this information to patients to provide an explanation for why the approach they have selected might not be working for them.
- The low-calorie diet approach
This is a potential game changer for people newly diagnosed (up to 6 years) with type 2 diabetes. The low-calorie diet induces rapid weight loss to put type 2 diabetes into remission (a non-diabetic state and no longer using antidiabetic drugs). It involves consuming a low-energy meal-replacement diet (for 12 to 20 weeks) that aims to achieve a target of 15kg weight loss. This is followed by a re-introduction to food (2 to 8 weeks), and behavioural support from a healthcare professional (e.g., nurse) to maintain weight loss. A large scale study of this diet found that almost half of participants achieved diabetes remission after 1 year. Recently published research has shown that these effects can be maintained for 2 years.
But which dietary approach is more effective? The answer is quite simply: the one that patients can adhere to and works best for them. Patients will have personal preferences and attitudes associated with the options for changing their diet, which will be influenced by their motivations for losing weight. Some will have a preference for a low-calorie diet to lose weight rapidly and avoid progression to insulin therapy, and the initial phase of the diet avoids the need to think about food choices and meal preparation. Others may prefer a low-carbohydrate approach because they want to learn to cook healthy meals, lose weight gradually and change the way they eat long-term. This approach also means eating meals throughout and not meal replacement products.
How do practitioners determine the right dietary approach for patients with type 2 diabetes, and provide them with appropriate support thereafter?
Practical recommendations
- It is important that practitioners are facilitators and not instructors. Avoid telling patients which dietary approach would be right for them. Seek to understand their personal motivations for weight loss, past experiences, preferences for dietary approach, and barriers to engaging in diet change.
- Provide patients with evidence-based information to help them to understand what they would have to do/learn for each dietary approach (e.g., see Diabetes UK information on low calorie diet and a low carbohydrate diet). This should include detailed information about the characteristics of each diet plan, including what potential side-effects they can expect, and the knowledge and skills that would need to be acquired to be successful.
- Ask open questions to elicit patients’ preferences for a specific diet plan, motivation for losing weight and barriers to engaging in dietary behavioural change:
- Which option would you be more likely to stick to?
- What do you hope to achieve from losing weight?
- What could prevent you from sticking to your chosen diet?
- Encourage patients to seek social support, e.g., do they have a partner, family member or friend who could provide them with emotional and practical support?
- Provide positive reinforcement where appropriate. This can include providing positive feedback on any effort the patient makes towards changing their diet (e.g., developing detailed plans to change diet); any successes (i.e. actual changes made to diet over a few days or weeks); and commenting positively on the beneficial impact of these changes on weight and glycemic control (i.e., any measurable changes).
