Diabetes and coeliac disease
The role of the dietitian is well documented in diabetes management and there are nutrition guidelines and recommendations for dietetic intervention in diabetes care (1,2). Nutrition advice must be adapted to the specific needs of the individual which may change with time and circumstances; for example age, pregnancy, nephropathy, intercurrent illness, and other conditions, such as coeliac disease. As there is a link between coeliac disease and Type 1 diabetes it is important that advice can be tailored to suit both conditions.
Energy balance and body weight
Dietary considerations for patients with coeliac disease and diabetes
Energy balance and body weight
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For those who are overweight (BMI > 25kg/m2), caloric intake should be reduced and energy expenditure increased so that BMI moves towards the recommended range.
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Prevention of weight regain is an important aim once weight loss has been achieved. Those patients who are unable to lose weight should be strongly encouraged to prevent further weight gain.
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Diabetic patients have a high proportion of intra-abdominal fat and associated increased health risks related to insulin resistance and associated dyslipidemia and hypertension. Waist circumference is therefore an important tool for assessing risk and for monitoring progress.
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Even modest weight loss of under 10% body weight improves insulin sensitivity, in addition to other health parameters, and should therefore be set as an initial goal for patients needing to lose weight.
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In patients with no evidence of nephropathy, protein intake may provide 10-20% of total energy.
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In patients with type 1 diabetes and evidence of established nephropathy, protein intakes should be at the lower end of the acceptable range (0.8g/kg normal body weight/day).
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Patients with diabetes, especially when poorly controlled or on haemodialysis, have increased protein turnover and their protein requirements may be greater than the recommended daily allowances. Protein intake should not be reduced below 0.6g/kg body weight/day.
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Saturated and trans fatty acids should provide less than 10% total daily energy. A lower intake may be beneficial if LDL-cholesterol is elevated.
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Monounsaturated fats are preferable fat sources and may provide up to 20% total energy, provided total fat intake does not contribute more than 35% total energy.
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Consumption of two to three servings of fish (preferably oily fish) each week will ensure an adequate intake of n-3 fatty acids. Plant sources of n-3 fatty acids include soya oil, walnuts, linseeds, and some green leafy vegetables.
Carbohydrate
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The recommended range of carbohydrate intake (45-60% total energy) is based on the limits for total fat and protein intakes.
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The consumption of carbohydrates with a low glycaemic index (GI) and high fibre content should be emphasised. Following a gluten-free diet can result in the elimination of main fibre-containing cereal products and therefore reduce fibre intake. The intake of foods such as pulses should be encouraged, both due to their high fibre content and low GI value.
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Most dietitians use a combination of methods when advising patients how to regulate their carbohydrate consumption e.g. qualitative advice based on the plate model; carbohydrate counting (with frequent glucose monitoring the insulin dependent patient can vary the amount of carbohydrate consumed or the time at which carbohydrates are eaten by adjusting insulin doses), 'exchanges', and the glycaemic index. Different approaches are required for different patients and in different circumstances.
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Carbohydrate counting gives greater dietary flexibility, while minimizing the frequency of hypoglycaemia and of peaks in blood glucose concentration, but does require intensive and time consuming assessment and teaching by experienced and highly trained staff.
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The glycaemic index is a useful way of quantifying the glycaemic effect of different carbohydrate foods. It is now well-established that dietary sucrose does not increase blood sugars more than isocaloric amounts of starch. It should be emphasized to patients that a low GI food will have less of a glycaemic effect than a high GI one if the foods are consumed in equi-carbohydrate loads. The GI should therefore not be used as a tool in isolation (2).
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For those patients with persistently raised triglyceride levels a carbohydrate intake at the lower end of the recommended range may be tried.
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Advice about sensible drinking given to the general population (maximum of 14 units per week for women and 21 units for men, with 1-2 alcohol-free days per week, avoidance during pregnancy and by those with gastritis, pancreatitis, severe liver disease) also applies to those with diabetes.
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Alcohol intake should be restricted in those patients who are trying to lose weight or who have significant hypertriglyceridemia or hypertension.
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When alcohol is taken by those on insulin it is most appropriately consumed with a carbohydrate-containing meal, because of the risk of hypoglycaemia. Delayed hypoglycaemia may occur up to 16 hours after drinking. The hypoglycaemic effect of alcohol is far less likely to occur in patients taking oral hypoglycaemic agents such as Metformin.
Dietary considerations for patients with coeliac disease and diabetes
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Blood glucose levels need to be monitored closely following coeliac disease diagnosis as insulin levels often need to be altered due to increased absorption of carbohydrate.
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Gluten-free alternatives to wheat-containing bread, pasta, biscuits and flour have approximately the same glycaemic index as their gluten-containing counter-parts, and therefore should not necessarily compromise the diet in terms of the GI (3).
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The patient should be encouraged to incorporate naturally gluten-free carbohydrate foods with low GI values in to their diet. These include: Pulses, legumes, buckwheat, rice i.e. basmati and wild, sweet potato, oats *, mung bean noodles, sweet corn, and fruit.
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Dietary intervention needs to take into account increased requirements for calcium to promote good bone health. An intake of 1000mg of calcium intake is recommended for adults with coeliac disease; or 1200mg for postmenopausal women and men over the age of 55 years. (4).
* Oats can be tolerated by the majority of people with coeliac disease but most oats are contaminated. Therefore a gluten-free source must be used.
References
1 Nutrition Subcommittee of the Diabetes Care Advisory Committee of Diabetes UK. The implementation of nutritional advice for people with diabetes. Diabetic Med 2003;20:786-807.
2 Mann JI et al. Evidence-based nutritional approaches to the treatment and prevention of diabetes mellitus. Nutr Metab Cardiavasc Dis 2004;14:373-394.
3 Packer SC et al. The glycaemic index of a range of gluten-free foods. Diabet Med 2000;17(9):657-60.
4. Lewis NR, Scott BB for the British Society of Gastroenterology (2007) Guidelines for osteoporosis in coeliac disease and inflammatory bowel disease. Accessed at www.bsg.org.uk
