No abstract

Many studies have shown high carbohydrate, high fibre diets to benefit diabetic control, the improvement being attributed mainly to an effect of fibre. This study investigated the possible beneficial effects of the digestible carbohydrate component. A diet rich in carbohydrate was compared with a traditional low carbohydrate diet in 10 Type 2 (non-insulin-dependent) diabetic patients, using a crossover design; both diets contained less than 20 g dietary fibre/day. During 24-h metabolic profiles carried out after 4 weeks on each diet, the mean basal plasma glucose (mean of 03.00, 05.00 and 07.00 h values) was 5.3 mmol/l on the high carbohydrate diet and 5.9 mmol/l on the low carbohydrate diet (p less than 0.05), despite the 2-h post-prandial glucose (mean of three main meals) being higher on the high carbohydrate diet than on the low carbohydrate diet (8.7 versus 7.3 mmol/l, p less than 0.01). Overall diabetic control was the same throughout the study, as judged by a mean 24-h plasma glucose of 6.7 mmol/l on the high carbohydrate and 6.6 mmol/l on the low carbohydrate diet, and haemoglobin A1c percentage of 8.3 on both diets. Mean cholesterol was 4.55 mmol/l on both diets and fasting plasma triglyceride was 2.83 mmol/l on the high carbohydrate and 2.55 mmol/l on the low carbohydrate diet (p = NS). These results indicate that a diet rich in carbohydrate, but restricted in fibre, does not cause overall deterioration of diabetic control or lipid metabolism in stable Type 2 diabetic patients, and suggest that digestible carbohydrate has an effect on basal blood glucose independent of fibre.

Fifteen non-insulin-dependent diabetic patients with persistently elevated blood glucoses despite high doses of oral hypoglycaemic agents, were randomly allocated to a high carbohydrate-high fibre diet (HC) or a reinforced low carbohydrate diet (LC). After six weeks the diets were reversed for a similar period. Immediately preceding the study and at the end of each dietary period 24-h biochemical profiles were performed. In the 11 patients who completed the study, fasting and preprandial glucose, percentage glycosylated haemoglobin, VLDL cholesterol and mean 24-h triglycerides were significantly lower on HC than on LC or during the initial profile on their usual diet. There was no significant difference in any of the measurements on LC compared with the usual diet. Previous studies of high carbohydrate-high fibre diets in diabetes have been carried out in relatively well-controlled patients. These data show that poorly controlled non-insulin-dependent patients have an even more striking response.

Twenty diabetic outpatients (12 non-insulin-treated and 8 insulin-treated) were given guar granulate in a dose of 10 g daily for two months in order to study the effect on glycaemic control and lipid levels. Mean glycosylated haemoglobin levels (HbAlc%) fell from 11.1±2.0% pre-guar to 10.5 ± 2.2% (P< 0.001) after one month on guar and to 10.1±2.3% ( P<0.0001) after two months. Following discontinuation of guar, HbAlc% rose to 11.1±2.5% ( P<0.002). However, there were no significant changes in fasting blood glucose, 1 h postprandial blood glucose following a test meal, 24 h urinary glucose excretion or in lipid levels. Gastrointestinal side effects occurred in 4 patients during treatment with guar. Four patients reduced their dose of insulin and 2 patients reduced their dose of sulphonylurea therapy during this time because of symptoms suggestive of hypoglycaemia. We suggest that the low dose of guar used in this study may help improve glycaemic control in diabetic patients and that this may be achieved with a low incidence of gastrointestinal side effects.