T M S Wolever

UNABSORBABLE CARBOHYDRATES AND DIABETES: DECREASED POST-PRANDIAL HYPERGLYCÆMIA

Two test meals were taken in random order on separate days by 8 non-insulin-requiring diabetic volunteers after 14-hour overnight fasts. Addition of 16 g guar and 10 g pectin to the control meal containing 106 g carbohydrate decreased markedly and significantly the rise in blood-glucose between 30 and 90 minutes and also resulted in significantly lower insulin levels between 30 and 120 minutes. When these meals were fed to 3 insulin-dependent diabetic subjects, a similar flattening of the post-prandial glucose rise ensued. This addition of certain forms of dietary fibre to the diet of diabetics significantly decreases post-prandial hyperglycaemia and would be expected to improve the control of blood-glucose concentration.

TREATMENT OF DIABETES WITH GUAR GUM: Reduction of Urinary Glucose Loss in Diabetics

When nine diabetic patients supplemented either their normal home diets (four patients) or metabolic ward diets (five patients) with 25 g guar gum daily for 5 or 7 days their mean urinary glucose excretion fell by 46% (P less than 0-05) and 54% (P less than 0-01), respectively. Gel-forming,, unabsorbable carbohydrate may therefore be a useful adjunct to anti-diabetic therapy, irrespective of the type of treatment or insulin dosage used.

Low glycemic index: lente carbohydrates and physiological effects of altered food frequency.

Many factors influence carbohydrate absorption. Slower rates of absorption may have advantages in reducing postprandial glycemia and insulinemia and, in time, reduce serum low-density-lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. Foods high in viscous fiber or antinutrients, or foods that are resistant to gelatinization, show slower rates of digestion and absorption and may be called low glycemic index or lente carbohydrate foods. Specific enzyme inhibitors may also cause lente effects. Certain small-intestinal effects of lente carbohydrate may be mimicked by altering feeding frequency (eg, nibbling vs gorging). Increased meal frequency reduces post-prandial insulin and glucose responses in people with non-insulin-dependent diabetes and in nondiabetic volunteers and lowers serum concentrations of LDL cholesterol and apolipoprotein B. Reduced hepatic cholesterol synthesis has been reported. Increased meal frequency may also slow small-intestinal absorption in the treatment of conditions such as diabetes, hyperlipidemia, and possibly obesity.

Improved glucose tolerance four hours after taking guar with glucose

SummaryTo gain some insights about the possible cumulative metabolic effect after a high-fibre meal, 6 subjects took two 80 g oral glucose loads, 4 h apart. Addition of 22.3 g guar to the first load decreased the rise in blood glucose and insulin after the second (guar-free) load by 50% (p<0.002) and 31% (p< 0.02) respectively. This corresponded with decreased 3-hydroxybutyrate levels at the start of the glucose tolerance test after guar (by 20%, p<0.02). When no guar was added to the first glucose load, both 3-hydroxybutyrate and non-esterified fatty acids tended to rise before the second test. No significant effect was seen in the responses of the gut hormones, gastric inhibitory peptide and enteroglucagon. Spreading the intake of the first 80 g of glucose over the initial 4 h (2 subjects) similarly flattened the glycaemic but increased the insulin response. The effect of guar on carbohydrate and fat metabolism, therefore, lasts at least 4 h and may result in improved carbohydrate tolerance to subsequent guar-free meals.

The glycaemic index values of foods containing fructose are affected by metabolic differences between subjects.

Background/Objectives:Glycaemic responses are influenced by carbohydrate absorption rate, type of monosaccharide absorbed and the presence of fat; the effect of some of these factors may be modulated by metabolic differences between subjects. We hypothesized that glycaemic index (GI) values are affected by the metabolic differences between subjects for foods containing fructose or fat, but not for starchy foods.Subjects/Methods:The GI values of white bread (WB), fruit leather (FL) and chocolate-chip cookies (CCC) (representing starch, fructose and fat, respectively) were determined in subjects (n=77) recruited to represent all 16 possible combinations of age (⩽40, >40 years), sex (male, female), ethnicity (Caucasian, non-Caucasian) and body mass index (BMI) (⩽25, >25 kg/m2) using glucose as the reference. At screening, fasting insulin, lipids, c-reactive protein (CRP), aspartate transaminase (AST) and waist circumference (WC) were measured.Results:There were no significant main effects of age, sex, BMI or ethnicity on GI, but there were several food × subject-factor interactions. Different factors affected each foods area under the curve (AUC) and GI. The AUC after oral glucose was related to ethnicity, age and triglycerides (r 2=0.27); after WB to ethnicity, age, triglycerides, sex and CRP (r 2=0.43); after CCC to age and weight (r 2=0.18); and after FL to age and CRP (r 2=0.12). GI of WB was related to ethnicity (r 2=0.12) and of FL to AST, insulin and WC (r 2=0.23); but there were no significant correlations for CCC.Conclusions:The GI values of foods containing fructose might be influenced by metabolic differences between –subjects, whereas the GI of starchy foods might be affected by ethnicity. However, the proportion of variation explained by subject factors is small.