Diabetes is a common health problem which affects around 3-4% of the UK population.
More than three-quarters of people with diabetes have type 2 diabetes (non-insulin dependent diabetes) and rely on diet and/or oral agents to control their blood glucose (blood ‘sugar’) levels. The majority of people with type 2 diabetes are overweight. Therefore, weight management is a crucial aspect in the prevention of type 2 diabetes and the management of diabetes in general.
Diabetes occurs when the pancreas - a gland situated behind the stomach - fails to produce enough of the hormone insulin to maintain control of blood glucose. In addition, many individuals are also insulin resistant, in which the body fails to respond adequately to its own insulin. The result is a rise in blood glucose level above the normal level.
There are two main types of diabetes:
Type 1 Diabetes
Develops when most or all of the cells in the pancreas that produce insulin are destroyed. It usually occurs in people under the age of 40, commonly during childhood, and is treated by regular insulin injections and a healthy diet.
Type 2 Diabetes
Develops when the pancreas still produces some insulin, but either in an inadequate amount or if its utilisation is less effective. It generally occurs in people over the age of 40 - occasionally in younger people - and is caused by a combination of factors, one being overweight. Type 2 diabetes can often be treated by a healthy diet alone, or by a combination of diet and medication or, in other cases, by diet and insulin injections.
Lifestyle recommendations for people with diabetes
The aim of nutritional management of diabetes is to optimise blood glucose control and reduce risk factors associated with heart and kidney disease. The diet for people with diabetes is no longer a special one, but merely follows the basic principles of healthy eating, ie a low-fat, high-carbohydrate diet. Research has shown that when people with type 2 diabetes consume higher carbohydrate intakes, the result is an increase in insulin and a reduction in free fatty acids, which could help slow down the progression of the disease.
The old idea that sugar causes diabetes was dismissed as long ago as 1989 by the UK Government’s COMA Committee (DoH 1989) . The FAO/WHO Expert Consultation on Carbohydrates in Human Nutrition reiterated in 1998 that sucrose, and other sugars, do not cause diabetes. The evidence available since these consultations does not merit any revision of that opinion (ADA 2008, Diabetes UK 2011). Furthermore, despite diabetes being a condition of blood glucose regulation, specific restriction of sugars is not necessary, except to ensure a balanced diet.
Achieving and maintaining a healthy body weight through diet and physical activity is of the utmost importance. Foods high in fat, which might predispose to obesity, are not encouraged, even though they might appear to have an advantage in not raising the level of glucose in the blood rapidly. Overweight individuals with diabetes should be encouraged to reduce their energy intake, by decreasing their dietary fat intake, and increase their physical activity levels, as even a modest weight loss (5-10%) will improve blood glucose control and other metabolic abnormalities associated with the disease. Research has shown that a weight loss of 10kg can reduce the risk from diabetes-related deaths by about a third.
The most recent Position Statement and Care Recommendations from Diabetes UK, utilises all the latest research to provide a comprehensive, evidence-based set of recommendations (Dyson et al. 2011).
The key dietary focus is to restrict the intake of saturated fats and replace with unsaturated fats, mainly monounsaturated. Risk of Type 2 diabetes can be significantly reduced by consuming a low fat diet and having increased physical activity.
The latest recommendations from Diabetes UK puts a greater emphasis on the total energy intake rather than source of energy in the diet to achieve glycemic control. Monitoring total carbohydrate intake, rather than source or type, is key.
One of the recent prominent changes in these guidelines and those from Europe and the USA, is the relaxation on dietary restriction of sugar and high-sugar content foods, providing blood glucose levels are kept in control. This is because sucrose (table sugar) does not increase blood glucose to a greater extent than similar amounts of starchy foods like bread, potatoes or rice. Fructose, sugar alcohols and other nutritive sweeteners, which are all energy sources, do not have substantial advantages over sucrose for people with diabetes and so should not be encouraged. However, non-nutritive sweeteners can be safely consumed within the recommended acceptable daily intake levels.
Physical activity and diabetes
People with diabetes should aim to participate in moderate-intensity physical activity for at least 20-30 minutes on most, and preferably all, days of the week. In addition, regular exercise is associated with a reduced risk of developing Type 2 diabetes, even in individuals who are overweight. Physical activity has been shown to improve insulin sensitivity, to acutely lower blood glucose, to favourably influence blood fat profiles, and to help weight control.