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Ten things you should know about diet and diabetes

Sarah Schenker
BSc SRD PhD
Nutrition Scientist British Nutrition Foundation
London
E:S.schenker@nutrition.org.uk

On diagnosis all people with diabetes should be referred to a state registered dietitian to receive specific dietary advice tailored to their individual needs. After diagnosis people with diabetes should continue to have regular reviews of their diet.

1. Achieve/maintain a healthy weight
The World Health Organization has defined the healthy range of body mass index for adults as 18.5-25, for both sexes.(1) Among the overweight, insulin sensitivity is decreased, and with it most aspects of diabetic control. Even modest weight loss of under 10% body weight improves insulin sensitivity and glucose tolerance, and reduces serum cholesterol and blood pressure.(2) People with diabetes, whether overweight or not, have a higher proportion of intra-abdominal fat than nondiabetic individuals of the same height and weight, and associated increased health risks related to more marked insulin resistance, associated dyslipidaemia and hypertension. There is evidence that weight loss leads to greater improvement in cardiac risk factors in individuals with higher waist-hip ratios.(3)

2. There is no special diet
Up until about 10-15 years ago people with diabetes were always advised to follow a very strict sugar-free diet and all sorts of special diabetic food products were available. Today the diet for people with diabetes is not a special diet, rather the healthy diet for people with diabetes is the healthy diet recommended for the general population. Although food choice and eating habits are important in helping to manage diabetes, people with the condition should be able to continue enjoying a wide variety of different foods as part of a balanced diet.
 
3. Meals based on starchy carbohydrate foods should be eaten regularly
Eating regular meals based on starchy foods such as bread, pasta, chapatis, potatoes, rice and cereals helps to control blood glucose levels. Where possible wholegrain or high-fibre varieties should be eaten as the fibre ­further helps control and maintains the health of the gastrointestinal tract. Research has shown that a carbohydrate intake that comprises over 50% of dietary energy is compatible with good diabetic control provided that the carbohydrate comes largely from complex sources, with a high intake of soluble fibre and resistant starch.(4)

4. Eat plenty of fruit and vegetables daily
A great deal of evidence suggests that people who eat diets rich in fruit and vegetables have lower rates of chronic diseases such as heart disease to which people with diabetes are at greater risk.(5) Scientists have attributed this not just to the important vitamins and minerals they provide such as folate and vitamin C, but also to other components they contain such as soluble fibre, which can help lower blood cholesterol levels, and naturally-occurring chemicals known collectively as phytochemicals. Phytochemicals have an antioxidant effect that may help combat free radical damage known to be involved in the initiation of these diseases. As with everyone, people with diabetes should aim to eat at least five portions of a variety of fruit and vegetables every day.

5. Fat intake should be reduced and modified
Most of the arguments for modifying dietary fat in the general population are considered to apply more strongly to people with diabetes. A decrease in saturates intake can reduce low-density lipid (LDL)-cholesterol and improve insulin sensitivity. Studies have shown that butter increases the insulin response more than olive oil (a rich source of monounsaturates), and large amounts also increase fatty acid and triglyceride concentrations, which in the long term may lead to hyperlipidaemia and reduced insulin sensitivity.(6)

6. Sugar and sugar-containing foods can be eaten but only in small amounts
People with diabetes do not need to eliminate sugar from their diet, it can be used as an ingredient in foods and in baking as part of a healthy diet. However, using sugar-free, low-sugar or diet squashes and carbonated drinks is desirable as sugar-containing drinks can cause blood glucose levels to rise quickly.

7. Salt intake should be reduced
High blood pressure is common in the UK and is a major risk factor for cardiovascular disease and premature death. A recent Scientific Advisory Committee on Nutrition report on salt confirmed previous advice that reducing current salt consumption by one third for adults, from around 9g/day to 6g/day, would have significant public health benefits by reducing the average population blood pressure levels. This would mean a reduction in the risk of stroke and heart disease for the UK population as a whole.
 
8. Only drink alcohol in sensible amounts
Precautions regarding alcohol intake that apply to the general public also apply to people with diabetes. For those who choose to drink alcohol, intakes of up to 15g of ethanol for women and 30g for men are acceptable for most.(7) When alcohol is taken by those on insulin it should be consumed with a meal including carbohydrate-containing foods because of the risks of potentially profound and prolonged hypoglycaemia.
Diabetes UK recommends:

  • No more than 14 units per week for women and 21 units per week for men, ie, two units per day for women and three units per day for men.
  • Avoid binge drinking, the units should be spread evenly over the week.
  • Two or three alcohol-free days each week, ­especially after an excess of alcohol.
  • Choosing the ordinary types of lager rather than the higher alcohol types.
  • Avoiding alcohol for those trying to lose weight or only having an occasional drink.
  • Never drinking on an empty stomach and topping up with a snack if necessary.
  • Having another snack (such as cereal or toast) before going to bed and checking blood glucose levels to reduce the risk of a hypo later on.

General recommendations regarding alcohol for people with diabetes are complicated by the fact that alcohol may have both unfavourable and beneficial effects. Alcohol may be an important energy source in overweight people. It can also be associated with raised blood pressure levels, increased triglycerides, an increased risk of hypoglycaemia and it favours fat deposition. Intakes of alcohol should be restricted in those with peripheral neuropathy and in pregnancy. On the other hand, moderate intake may be beneficial by elevating levels of high-density lipid (HDL)-cholesterol, reducing coagulability and decreasing lipid oxidation through the antioxidant nutrients found in some alcoholic drinks. Recommendations should depend on the characteristics of the individual patient, and the socioeconomic consequences of overconsumption should not be forgotten.

9. Foods with a low glycaemic index can help control blood glucose levels
The glycaemic index (GI) was proposed in 1981 as a method to guide food selection by assessing and classifying the glycaemic response to the amount of food containing a standard carbohydrate load, in relation to the glycaemic effect of the same amount of reference food, eg, white bread. The use of low GI staple foods to form the basic and major component of each meal offers benefits of lipid reduction and improvements in glycaemic control.(8) A food's GI is affected by the rate of digestion and absorption of the carbohydrate present in it, which in turn is influenced by factors such as amount of food eaten, presence of fat, protein, type of starch and method of processing and cooking.(9) However, the a food's acceptability should not be determined on the basis of GI alone - some foods with high GI values, such as bread and potatoes, are desirable for other reasons.
 
10. "Diabetic" foods are unnecessary
Historically, when sugar avoidance was recommended, a market built up for special foods that contained sugar substitutes. Many of these foods remain available and are bought by people with diabetes or their relatives in the mistaken belief that they are beneficial. Most so-called diabetic foods offer no reduction in energy, in fact some are higher, and they are more expensive than normal alternatives. There are no health benefits ­associated with the consumption of these foods.

References

  1. WHO. Diet, nutrition and prevention of chronic disease. Technical report series 797. Geneva: WHO; 1990.
  2. Goldstein DJ. Beneficial health effects of modest weight loss. Int J Obesity 1992;16:397-415.
  3. Lean MEJ, et al. Waist ­circumference as a measure for indicating need for weight ­management. BMJ 1995;311:158-61.
  4. Howard BV, et al. Evaluation of metabolic effects of substitution of complex carbohydrates for saturated fat in individuals with obesity and NIDDM. Diabetes Care 1991;14:786-95.
  5. British Nutrition Foundation. Plants: diet and health. London: BNF; in press.
  6. Rasmussen O, et al. Differential effects of saturated and monounsaturated fat on blood glucose and insulin responses in subjects with NIDDM. Am J Clin Nutr 1996;63:249-53.
  7. The Diabetes and Nutrition Study Group of the European Association for the Study of Diabetes. Recommendations for the nutritional management of patients with diabetes mellitus. Eur J Clin Nutr 1999;54:353-5.
  8. Frost G, et al. Dietary advice based on the glycaemic index improves dietary profile and metabolic control in type 2 diabetes mellitus. Diabetic Med 1994;11:397-401.
  9. Hermansen K. Research ­methodologies in the evaluation of intestinal glucose absorption and the concept of glycaemic index. In: Morgensen CE, Standl E, editors. Research ­methodologies in human diabetes. Berlin: Walter de Gruyter; 1994. p. 205-18.

Resources
Scientific Advisory Committee on Nutrition
W:www.sacn.gov.uk

Diabetes UK
W:www.diabetes.org.uk