Digestible carbohydrate ? an independent effect on diabetic control in type 2 (non-insulin-dependent) diabetic patients?

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.

Dietary Fiber in Management of Diabetes

“…Addition of purified viscous fiber to metabolic diets resulted in reduced urinary losses of glucose and ketone bodies (25). The results of these studies have been confirmed by others (26)(27)(28)(29)(30)(31).…”

Dietary carbohydrate: relationship to cardiovascular disease and disorders of carbohydrate metabolism

“…This is surprising, given that in the late 1980s, it had been clearly shown that high carbohydrate diets were only associated with beneficial effects in terms of glycaemic control and blood lipids when carbohydrate was derived principally from foods rich in soluble forms of dietary fibre, notably pulses, legumes and intact fruits and vegetables (Rivellese et al, 1980;Simpson et al, 1981;Riccardi et al, 1984;Mann, 2001). Higher intakes of cereal (insoluble) fibre were associated with less marked or no benefit in glucose or lipid levels (Simpson et al, 1979;1982;Riccardi et al, 1984). The beneficial effects of soluble forms of dietary fibre derived from fruits and vegetables appear to have been rediscovered more recently in randomized crossover studies in type II diabetes (Chandalia et al, 2000).…”

Dietary fibre and diabetes revisited

“…In fact such observations were not entirely new, similar observations having been made many years earlier by Kempner using his rice diet (Kempner et al, 1958). Inspired by the work of Anderson and also by the studies of Stone and Connor (1963), who drew attention to the potential of the low carbohydrate -high fat diet, then in widespread use, to increase cardiovascular risk, our own group in Oxford, England embarked on a series of carefully controlled studies which helped to further understand the role of dietary fibre (Simpson et al, 1979a;Simpson et al, 1979b;Simpson et al, 1981;Simpson et al, 1982;Lousley et al, 1984;Geekie et al, 1986;Mann, 1984). Each of the studies involved a crossover design in which patients with type 1 and type 2 diabetes were randomised to receive advice regarding the standard diabetic diet of the time, relatively low in carbohydrate and dietary fibre, or an experimental high carbohydrate diet.…”

“…The improvement was particularly striking when foods rich in soluble fibre were encouraged (Simpson et al, 1981). The early studies were criticised on the grounds that we could not distinguish between the beneficial effects of carbohydrates per se and dietary fibre, but later studies in which carbohydrate alone was increased left little doubt that in order to achieve improved glycaemic control and reduced LDL without any increase in VLDL and triglycerides or reduction in HDL it was essential to increase dietary fibre, especially soluble fibre (Simpson et al, 1982). We were also able to show that it was possible to achieve beneficial effects with more acceptable amounts of dietary fibre than had been used in our earlier studies (Lousley et al, 1984).…”