High-carbohydrate diets and insulin-dependent diabetics

Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses

BACKGROUND

Fibre is promoted as part of a healthy dietary pattern and in diabetes management. We have considered the role of high-fibre diets on mortality and increasing fibre intake on glycaemic control and other cardiometabolic risk factors of adults with prediabetes or diabetes.

METHODS AND FINDINGS

We conducted a systematic review of published literature to identify prospective studies or controlled trials that have examined the effects of a higher fibre intake without additional dietary or other lifestyle modification in adults with prediabetes, gestational diabetes, type 1 diabetes, and type 2 diabetes. Meta-analyses were undertaken to determine the effects of higher fibre intake on all-cause and cardiovascular mortality and increasing fibre intake on glycaemic control and a range of cardiometabolic risk factors. For trials, meta regression analyses identified further variables that influenced the pooled findings. Dose response testing was undertaken; Grading of Recommendations Assessment, Development and Evaluation (GRADE) protocols were followed to assess the quality of evidence. Two multicountry cohorts of 8,300 adults with type 1 or type 2 diabetes followed on average for 8.8 years and 42 trials including 1,789 adults with prediabetes, type 1, or type 2 diabetes were identified. Prospective cohort data indicate an absolute reduction of 14 fewer deaths (95% confidence interval (CI) 4-19) per 1,000 participants over the study duration, when comparing a daily dietary fibre intake of 35 g with the average intake of 19 g, with a clear dose response relationship apparent. Increased fibre intakes reduced glycated haemoglobin (HbA1c; mean difference [MD] -2.00 mmol/mol, 95% CI -3.30 to -0.71 from 33 trials), fasting plasma glucose (MD -0.56 mmol/L, 95% CI -0.73 to -0.38 from 34 trials), insulin (standardised mean difference [SMD] -2.03, 95% CI -2.92 to -1.13 from 19 trials), homeostatic model assessment of insulin resistance (HOMA IR; MD -1.24 mg/dL, 95% CI -1.72 to -0.76 from 9 trials), total cholesterol (MD -0.34 mmol/L, 95% CI -0.46 to -0.22 from 27 trials), low-density lipoprotein (LDL) cholesterol (MD -0.17 mmol/L, 95% CI -0.27 to -0.08 from 21 trials), triglycerides (MD -0.16 mmol/L, 95% CI -0.23 to -0.09 from 28 trials), body weight (MD -0.56 kg, 95% CI -0.98 to -0.13 from 18 trials), Body Mass Index (BMI; MD -0.36, 95% CI -0·55 to -0·16 from 14 trials), and C-reactive protein (SMD -2.80, 95% CI -4.52 to -1.09 from 7 trials) when compared with lower fibre diets. All trial analyses were subject to high heterogeneity. Key variables beyond increasing fibre intake were the fibre intake at baseline, the global region where the trials were conducted, and participant inclusion criteria other than diabetes type. Potential limitations were the lack of prospective cohort data in non-European countries and the lack of long-term (12 months or greater) controlled trials of increasing fibre intakes in adults with diabetes.

CONCLUSIONS

Higher-fibre diets are an important component of diabetes management, resulting in improvements in measures of glycaemic control, blood lipids, body weight, and inflammation, as well as a reduction in premature mortality. These benefits were not confined to any fibre type or to any type of diabetes and were apparent across the range of intakes, although greater improvements in glycaemic control were observed for those moving from low to moderate or high intakes. Based on these findings, increasing daily fibre intake by 15 g or to 35 g might be a reasonable target that would be expected to reduce risk of premature mortality in adults with diabetes.

Dietary fibre in foods: a review

Dietary fibre is that part of plant material in the diet which is resistant to enzymatic digestion which includes cellulose, noncellulosic polysaccharides such as hemicellulose, pectic substances, gums, mucilages and a non-carbohydrate component lignin. The diets rich in fibre such as cereals, nuts, fruits and vegetables have a positive effect on health since their consumption has been related to decreased incidence of several diseases. Dietary fibre can be used in various functional foods like bakery, drinks, beverages and meat products. Influence of different processing treatments (like extrusion-cooking, canning, grinding, boiling, frying) alters the physico- chemical properties of dietary fibre and improves their functionality. Dietary fibre can be determined by different methods, mainly by: enzymic gravimetric and enzymic-chemical methods. This paper presents the recent developments in the extraction, applications and functions of dietary fibre in different food products.

Carbohydrate terminology and classification

Dietary carbohydrates are a group of chemically defined substances with a range of physical and physiological properties and health benefits. As with other macronutrients, the primary classification of dietary carbohydrate is based on chemistry, that is character of individual monomers, degree of polymerization (DP) and type of linkage (alpha or beta), as agreed at the Food and Agriculture Organization/World Health Organization Expert Consultation in 1997. This divides carbohydrates into three main groups, sugars (DP 1-2), oligosaccharides (short-chain carbohydrates) (DP 3-9) and polysaccharides (DP> or =10). Within this classification, a number of terms are used such as mono- and disaccharides, polyols, oligosaccharides, starch, modified starch, non-starch polysaccharides, total carbohydrate, sugars, etc. While effects of carbohydrates are ultimately related to their primary chemistry, they are modified by their physical properties. These include water solubility, hydration, gel formation, crystalline state, association with other molecules such as protein, lipid and divalent cations and aggregation into complex structures in cell walls and other specialized plant tissues. A classification based on chemistry is essential for a system of measurement, predication of properties and estimation of intakes, but does not allow a simple translation into nutritional effects since each class of carbohydrate has overlapping physiological properties and effects on health. This dichotomy has led to the use of a number of terms to describe carbohydrate in foods, for example intrinsic and extrinsic sugars, prebiotic, resistant starch, dietary fibre, available and unavailable carbohydrate, complex carbohydrate, glycaemic and whole grain. This paper reviews these terms and suggests that some are more useful than others. A clearer understanding of what is meant by any particular word used to describe carbohydrate is essential to progress in translating the growing knowledge of the physiological properties of carbohydrate into public health messages.

Nutrition in patients with Type 2 diabetes: are low-carbohydrate diets effective, safe or desirable?

Low-carbohydrate diets have been around for over 100 years. They have become very popular recently but the scientific basis for their use remains to be fully established. This article reviews the recent trials that have been published and also what is known about the effects of low-carbohydrate, high-protein diets on energy expenditure and body composition. Although many controversies remain, there is now mounting evidence that these diets can lead to effective weight loss and may thus be a useful intervention for patients who have, or are at risk of, diabetes. The practical aspects of using these diets as a short- to medium-term intervention are discussed.

Cereal grains, legumes and diabetes

This review examines the evidence for the role of whole grain foods and legumes in the aetiology and management of diabetes. MedLine and SilverPlatter ('Nutrition' and 'Food Science FSTA') databases were searched to identify epidemiological and experimental studies relating to the effects of whole grain foods and legumes on indicators of carbohydrate metabolism. Epidemiological studies strongly support the suggestion that high intakes of whole grain foods protect against the development of type II diabetes mellitus (T2DM). People who consume approximately 3 servings per day of whole grain foods are less likely to develop T2DM than low consumers (<3 servings per week) with a risk reduction in the order of 20-30%. The role of legumes in the prevention of diabetes is less clear, possibly because of the relatively low intake of leguminous foods in the populations studied. However, legumes share several qualities with whole grains of potential benefit to glycaemic control including slow release carbohydrate and a high fibre content. A substantial increase in dietary intake of legumes as replacement food for more rapidly digested carbohydrate might therefore be expected to improve glycaemic control and thus reduce incident diabetes. This is consistent with the results of dietary intervention studies that have found improvements in glycaemic control after increasing the dietary intake of whole grain foods, legumes, vegetables and fruit. The benefit has been attributed to an increase in soluble fibre intake. However, prospective studies have found that soluble fibre intake is not associated with a lower incidence of T2DM. On the contrary, it is cereal fibre that is largely insoluble that is associated with a reduced risk of developing T2DM. Despite this, the addition of wheat bran to the diets of diabetic people has not improved indicators of glycaemic control. These apparently contradictory findings might be explained by metabolic studies that have indicated improvement in glucose handling is associated with the intact structure of food. For both grains and legumes, fine grinding disrupts cell structures and renders starch more readily accessible for digestion. The extent to which the intact structure of grains and legumes or the composition of foods in terms of dietary fibre and other constituents contribute to the beneficial effect remains to be quantified. Other mechanisms to help explain improvements in glycaemic control when consuming whole grains and legumes relate to cooking, type of starch, satiety and nutrient retention. Thus, there is strong evidence to suggest that eating a variety of whole grain foods and legumes is beneficial in the prevention and management of diabetes. This is compatible with advice from around the world that recommends consumption of a wide range of carbohydrate foods from cereals, vegetables, legumes and fruits both for the general population and for people with diabetes.

Carbohydrate and Fiber Recommendations for Individuals with Diabetes: A Quantitative Assessment and Meta-Analysis of the Evidence

To review international nutrition recommendations with a special emphasis on carbohydrate and fiber, analyze clinical trial information, and provide an evidence-based recommendation for medical nutrition therapy for individuals with diabetes. Relevant articles were identified by a thorough review of the literature and the data tabulated. Fixed-effects meta-analyses techniques were used to obtain mean estimates of changes in outcome measures in response to diet interventions. Most international organizations recommend that diabetic individuals achieve and maintain a desirable body weight with a body mass index of </=25 kg/m(2). For diabetic subjects moderate carbohydrate, high fiber diets compared to moderate carbohydrate, low fiber diets are associated with significantly lower values for: postprandial plasma glucose, total and low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. High carbohydrate, high fiber diets compared to moderate carbohydrate, low fiber diets are associated with lower values for: fasting, postprandial and average plasma glucose; hemoglobin A(1c); total, LDL-cholesterol, HDL-cholesterol and triglycerides. Low glycemic index diets compared to high glycemic index diets are associated with lower fasting plasma glucose values and lower glycated protein values. Based on these analyses we recommend that the diabetic individual should be encouraged to achieve and maintain a desirable body weight and that the diet should provide these percentages of nutrients: carbohydrate, >/=55%; protein, 12-16%; fat, <30%; and monounsaturated fat, 12-15%. The diet should provide 25-50 g/day of dietary fiber (15-25 g/1000 kcal). Glycemic index information should be incorporated into exchanges and teaching material.

Usual dietary intake and hemoglobin A1 level in patients with insulin-dependent diabetes

OBJECTIVE

To explore epidemiologic evidence for the relationship between dietary intake and glycemic control.

DESIGN/SUBJECTS

We examined usual dietary intake, assessed by a food frequency questionnaire, from a random sample (n = 136) of patients who had had insulin-dependent diabetes mellitus for 15 to 21 years.

RESULTS

In men, absolute intakes of energy, carbohydrate, protein, fat, and dietary fiber were positively correlated with hemoglobin A1 (HbA1) (P < .05); Spearman correlation coefficients (rs) were .28, .22, .28, .34, and .25, respectively. In women, the correlations were weaker and not significant; rs values were .18, .13, .17, .19, and .16, respectively. When these nutrients were expressed as a percentage of energy or as an amount per 1,000 kcal, only percentage of energy from fat showed a significant association with HbA1--but only in men (rs = .23 for men and .02 for women). Adjustment for body weight, insulin dose, and physical activity using multiple regression analysis did not change the relationship between HbA1 and intakes of energy and fat. Sucrose and alcohol intakes did not show any association with HbA1.

CONCLUSIONS

Among men with insulin-dependent diabetes mellitus, the major dietary correlates of poor glycemic control were high intake of energy and percentage of energy from fat. Further investigation is needed to confirm this relationship of energy, fat, and glycemic control.

The influence of dietary education in diabetic children

The aim of our study was to evaluate the efficacy of dietary education in inducing modification of the diet and to measure biochemical parameters in 36 children and adolescents with IDDM. At the beginning of the study, each patient was evaluated as follows: food intake (by the method of the 24-h recall for 3 days), auxological parameters, biochemical parameters. Thereafter a program of nutritional guidelines was provided. Subsequent meetings took place at 1-month-intervals. The study ended 3 months later, when all the parameters were completely revalued. We observed improved nutrition in our patients both in terms of total caloric intake and calorie distribution. In particular there was an increase in carbohydrates and a reduction in lipids, reaching the percentage levels recently recommended. With a reduction in lipid intake a significant decrease in LDL cholesterol and a significant increase in HDL cholesterol were noticed in our patients. These modifications are very important for the prevention of arteriosclerosis and thus macrovascular disease. We maintain that dietary education plays an important role in helping children and adolescents with IDDM to follow a suitable diet.

Treatment of lipid disorders in diabetes mellitus

One reason for premature atherosclerosis in patients with diabetes mellitus is abnormal lipid metabolism. This article discusses the plasma lipid disorders associated with diabetes mellitus, and how to apply the new guidelines from the National Cholesterol Education Program for treatment of hypercholesterolemia in patients with diabetes mellitus.

Does adding fibre to a low energy, high carbohydrate, low fat diet confer any benefit to the management of newly diagnosed overweight type II diabetics?

The effect of supplementing a low energy (roughly 5.0 MJ), high carbohydrate (180 g), low fat (roughly 25 g) diet with 10-15 g of either cereal fibre or guar gum was investigated in 24 newly diagnosed overweight non-insulin-dependent (type II) diabetics. The patients were divided into three treatment groups: one received a low fibre control diet throughout the study period of 20 weeks and the other received two supplements of cereal fibre and guar gum in a crossover manner. The nutrient content of the diets was kept constant throughout. Though patients taking the low fibre diet showed a smaller reduction in fasting plasma glucose concentrations over the first eight weeks than patients taking a high fibre diet, this difference was not evident at the end of 20 weeks; reductions in weight and glycated haemoglobin values were similar for each dietary regimen throughout the trial. There was little evidence that supplementing a low energy, high carbohydrate diet with fibre confers any therapeutic benefit to type II diabetics and no evidence that taking fibre as viscous polysaccharides is any more beneficial to overweight diabetics than taking a similar fibre supplement as cereal. On the contrary, guar gum caused more abdominal discomfort and flatulence than the other diets.

The glycemic index: similarity of values derived in insulin-dependent and non-insulin-dependent diabetic patients

To see whether relative differences in the glycemic responses to different foods were similar in insulin-dependent (IDDM) and non-insulin-dependent diabetic patients (NIDDM) we determined the glycemic index (GI) of a total of 20 foods and mixed test meals in groups of IDDM and NIDDM volunteers. The mean GI values ranged from 32 in NIDDM and 41 in IDDM (pearled barley) to 105 in NIDDM and 111 in IDDM (bread with cheese and tomato). The correlation between the mean GI values in IDDM and NIDDM was highly significant (r = 0.927, p less than 0.001). The mean GI values for 15 of the 20 test meals was greater in IDDM than in NIDDM (mean of GI for all 20 foods, 76 in IDDM compared with 68 in NIDDM, p less than 0.005). However, the difference in GI between IDDM and NIDDM was t statistically significant for 19 of the 20 individual test meals. Greater within-individual variability of glycemic responses in IDDM probably accounts for the slightly greater mean GI value seen in IDDM compared with NIDDM. The addition of 32 g cheddar cheese to four foods which were also fed without cheese had no significant effect on the GI in NIDDM (mean GI of 68 without cheese compared with 72 for the meals with cheese), but had a small effect in IDDM where the mean GI was increased from 72 to 87 (p less than 0.05). However, despite small increases in glycemic response to foods with added cheese, the relative differences between foods were unaffected by the addition of cheese in both IDDM and NIDDM. It is concluded that mean GI values for foods are very similar in IDDM and NIDDM patients.

Effect of short-term consumption of a high-fat, low-carbohydrate diet on metabolic control in insulin-deficient diabetic rats

This study examined the effect of changing the proportion of dietary fat on metabolic control in rats rendered mildly diabetic with streptozotocin (STZ). The high-fat (HF) diet contained 66% energy as fat and 12% as carbohydrate while the low-fat (LF) diet contained 12% energy as fat and 66% as carbohydrate. Both diets had a P/S ratio of 1:3. Young male rats weighing 100 g were treated with STZ (60 mg/kg IV) and randomly allocated to either the LF of HF diet. After 2 weeks, the fasting plasma glucose concentrations were significantly higher in the HF-STZ rats than in the LF-STZ rats (13.2 +/- 1.2 mmol/L v 7.1 +/- 0.8 mmol/L, respectively, P less than 0.001). The increase in plasma glucose above the basal level following the intravenous glucose load (0.5 g/kg body wt) was similar in both groups of STZ-treated rats and glucose clearance was similarly impaired. The fall in glucose concentrations in the 30 minutes following the IV insulin (0.5 U Actrapid insulin/kg body wt) was greater in the LF-STZ rats (delta AUC = -1.60 +/- 0.20 mmol/L 0.5h) than in the HF-STZ group (delta AUC = -0.97 +/- 0.20 mmol/L 0.5 h, P less than 0.05) and either of the control groups (delta AUC = -0.94 +/- 0.37, -0.83 +/- 0.09 mmol/L 0.5 h for LF and HF rats, respectively, P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

High-carbohydrate and fibre diets in the treatment of diabetes

After Kinsell and collaborators (1970) demonstrated a smaller glycaemic rise in diabetic subjects given larger rather than smaller nutrient loads (because of the more complicated composition of the intakes) notions that one can usefully prescribe diabetic diets from crude chemical composition of foods 'on the shelf' have been abandoned, with greater consideration of the varied gastro-intestinal handling of foods, how they are changed by cooking, etc., the way different food interact within the gastro-intestinal tract, and the importance of specific chemical constitution, both of the classical nutrients as well as fibre contents. In practice, high-carbohydrate diets are usually entwined with high-fibre intake. Apart from the observations on the practicability of high-carbohydrate diets in obtaining successful glycaemic control of diabetics outside the 'First World', doubts were voiced in the late 1920s concerning the wisdom of the high-fat intake accompanying low-carbohydrate diets. In the next decade Himsworth showed in normal subjects that high-carbohydrate intake improved glucose tolerance, and this has been repeated in Seattle. Data concerning complete meals or, much better, dietary regimes persisted with over long periods of time are more relevant than those from single intakes of liquid homogenates. We present observations on 6-week intakes of particular dietary regimes (in free-living patients) from which the main conclusions would seem: a high-carbohydrate intake does no harm to glycaemic control in diabetics, providing it is predominantly of polysaccharides; a high-fibre intake has various beneficial effects, and in particular high viscous fibre intake reduces post-prandial glycaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

[Current trends in dietetics in diabetology and their experimental bases]

The last decade has witnessed drastic changes in our views on diet for diabetics, whether insulin-dependent or not. To bring blood glucose levels down to normal values, thereby preventing diabetic microangiopathy or alleviating its course, remains the compelling purpose of treatment, but the modalities and constraints of the dietetic measures which contribute to this result have been radically revised. Leaving aside fashions and controversies, three tendencies have emerged: the low carbohydrate diet does not improve the glycaemic balance but implies an excessive fat intake which may aggravate the microangiopathy. Of course, an hypocaloric diet remains fundamental in the management of obese non-insulin dependent diabetics; the effects on glycaemia of the carbohydrate ration constituents must be reconsidered. The classical distinction between "fast" and "slow" sugars seems to be excessive and insufficient, if not erroneous. Food replacements must take into account the glycaemic index; a minimal dietary fibre intake has a favourable effect on post-prandial glycaemia and lipid metabolism and is to be recommended, notably to diabetics.

The effects of carbohydrate-enriched meals on glucose turnover and metabolic clearance rates of glucose in type 2 diabetic patients

The addition of fructose to natural meals elicits lower serum glucose and immunoreactive insulin responses when compared with that of sucrose and starch meals. Differences in rates of splanchnic glucose appearance and peripheral glucose disposal may be partly responsible. To evaluate the role of both parameters after different carbohydrate-enriched meals, we measured the arterialized venous blood glucose, immunoreactive insulin and gastric inhibitory polypeptide concentrations in seven Type 2 diabetic patients after ingestion of isocaloric test meals. Measurements were made in a random manner on three separate occasions. Fructose, sucrose, and bread supplementation constituted 68% of the total carbohydrate content of each meal. Rates of total glucose appearance, glucose utilization and metabolic clearance rates of glucose were determined by the D3-H-3 glucose prime-continuous infusion technique. The mean fasting glucose levels were similar in the three groups. Mean peak glucose concentrations and integrated incremental areas were significantly lower (p less than 0.02) after the fructose-enriched meals compared with that of either sucrose or bread. The basal arterialized venous blood glucose levels were similar in all three groups. The mean incremental integrated arterialized venous blood glucose area was significantly lower in the fructose group when compared with the sucrose (p less than 0.05) and bread (p less than 0.02) groups. The mean fasting gastric inhibitory polypeptide levels were similar in the three groups. However, the mean incremental integrated gastric inhibitory polypeptide areas were significantly lower in the fructose group compared with the sucrose and bread groups (p less than 0.01 and p less than 0.05 respectively). Basal hepatic glucose outputs were not significantly different in the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Acceptability of high-fibre diets in diabetic patients

Twenty-five diabetic patients were selected from Oxford Diabetic Clinics to assess their dietary compliance (Group A). All had been taught to follow diets rich in dietary fibre in which carbohydrate provided 50% of total energy. The results were compared with those obtained previously from a similar group of patients (Group B) all of whom had been instructed to follow a diet in which carbohydrate provided 40% of total energy. The patients of Group A had a significantly greater intake of carbohydrate (45.1% vs 34.7% of total energy) and dietary fibre (33.1 g vs 18.7 g) and a lower intake of fat (33.5% vs 42.1% of total energy) than the patients of Group B. The results of dietary assessment obtained from a third group of patients (Group C), who had been advised to follow a high-fibre diet before the widespread availability of dietary teaching aids and recipe books, showed that carbohydrate and fat provided 37.5% and 41.0% of total energy, with a dietary fibre intake of 25.6 g. The results suggest that patients are willing and able to change their dietary habits towards a distribution of food constituents likely to improve diabetic control and reduce the risk of coronary heart disease when given enthusiastic instruction and support in diabetic clinics.

Epidemiological and clinical studies on optimal nutrition in diabetes

There would seem to be little doubt that a diet high in fiber-rich carbohydrate can improve diabetic control and reduce levels of LDL cholesterol when compared with the more traditional low carbohydrate-high fat diabetic diet. The abnormalities of platelet function in diabetes and their association with certain essential fatty acids suggest that attention to the nature of the fat composition of the diet may be equally relevant in attempts to reduce the frequency of both micro- and macrovascular complications of diabetes. Only a very limited number of intervention studies have been carried out. More information is urgently required concerning the effects of modifying the fatty acid composition of the diabetic diet.

The effects of a high-carbohydrate low-fat cholesterol-restricted diet on plasma lipid, lipoprotein, and apoprotein concentrations in insulin-dependent (type I) diabetes mellitus

Six women with well-defined insulin-dependent diabetes mellitus (IDDM) were studied for 4 weeks during a control diet containing 45% of the calories as carbohydrate, 40% fat (P/S ratio 0.14), 15% protein, and 580 mg of cholesterol, and for 6 weeks during a high-carbohydrate low-fat cholesterol-restricted diet with 65% carbohydrate, 20% fat (P/S ratio 1.40), 15% protein, and 62 mg cholesterol. All subjects completed both dietary periods in a crossover experimental design. Individual menus were subject-selected from a calculated exchange list containing conventional food items consistent with current American dietary patterns. The diets were well-tolerated by all subjects. Total plasma cholesterol decreased from 201 to 156 mg/100 mL (P less than 0.05) during the cholesterol-restricted diet, while total plasma triglyceride (TG) increased from 96 to 115 mg/100 mL (P less than 0.01). During this same period, very low-density lipoprotein cholesterol (VLDL-C) and VLDL-TG increased from 17 to 21 mg/100 mL (P less than 0.05) and from 59 to 76 mg/100 mL (P less than 0.001), respectively, while low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) decreased from 126 to 90 mg/100 mL (P less than 0.05) and from 50 to 39 mg/100 mL (P less than 0.05), respectively. LDL-C/HDL-C and total-C/HDL-C ratios were lower but not significantly different, and LDL-TG and HDL-TG were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Postprandial hyperglycemia after ingestion of peeled and non-peeled fruits in type-2 diabetics

Should diabetics prefer nonpeeled fruits in their diet? To answer this question 27 type-2 diabetics divided into three groups were examined on two different occasions under the same fasting conditions. The first group of patients received 300g of pears with peel and on another day 300g of peeled pears. The second group ate 300g of pears with peel and 230g of peeled pears (the 70g difference represents the weight of the peel). The third group of diabetics consumed 300g of apples with peel and 300g of apples without peel. Blood samples were collected before and 20, 40, 60, 80, 100, 120 and 140 min after fruit ingestion. No significant differences were noted in terms of mean blood glucose, serum insulin and serum triglyceride levels among the two meals (fruits with or without peel). This observation was confirmed in all groups studied. Peeled and nonpeeled fruits appear to produce the same hyperglycemia in type-2 diabetics, in spite of the high fiber content of the peel. Therefore, the suggestion of reducing postprandial hyperglycemia in diabetics by eating nonpeeled fruits does not seem to be justified.

Glycaemic effects of bread and marmalade in insulin-dependent diabetes

The glycaemic responses of 12 C-peptide negative insulin-dependent diabetics were studied following four breakfasts with different carbohydrate sources. Total energy content of the meals was the usual for each subject, carbohydrate supplying 55% and fat 32%. The meals comprised: wholemeal bread with margarine; white bread with margarine; marmalade made with sucrose, and cheddar cheese; and marmalade (22% of total energy) on wholemeal bread with margarine. The study demonstrated powerfully that there were no statistically significant or clinically relevant differences between the meals in post-prandial glucose peak elevation, or in incremental area under the blood glucose curve to 120 mins. On these grounds, sucrose, in amounts considered acceptable to the general population, need not be prohibited from diabetic diets.

A controlled trial of a high fibre, low fat and low sodium diet for mild hypertension in Type 2 (non-insulin-dependent) diabetic patients

Fifty hypertensive Type 2 (non-insulin-dependent) diabetic patients were allocated, in a controlled trial, to a treatment diet of high fibre, low fat and low sodium composition, or to a control diet by the hospital dietitian. After 3 months treatment, the modified diet-treated group showed a highly significant reduction in mean systolic (180.5 +/- 19.0 to 165.0 +/- 20.7 mmHg) and diastolic blood pressure (96.6 +/- 9.3 to 88.0 +/- 10.5 mmHg), accompanied by significant reductions in urinary sodium excretion (183.0 +/- 62.1 to 121.7 +/- 65.8 mmol/day) glycosylated haemoglobin (12.4 +/- 3.1 to 10.5 +/- 2.9%), weight (74.6 +/- 13.5 to 71.7 +/- 12.1 kg) and serum triglyceride levels (p less than 0.05). The mean values of diastolic pressure (p less than 0.01), urinary sodium/potassium ratio (p less than 0.001), urinary potassium (p less than 0.01) was significantly reduced at 3 months compared to control. No changes in serum HDL-cholesterol levels were observed. The number of patients with normal blood pressure at 3 months was greater in the modified diet-treated group (ten versus five). Treatment of mild hypertension in diabetic subjects with this form of dietary regimen has a hypotensive response, with improvement in glycaemic control and no side effects. This modified diet may be an attractive alternative to anti-hypertensive drug therapy as a first line treatment.

Infant adiposity and maternal energy consumption in well-controlled diabetics

This study was designed to determine the relationship of maternal diet and infant adiposity in well-controlled diabetics. The relationship between the fat consumption pattern of the pregnant diabetic and the adiposity of her infant was investigated. Length, weight, and head circumference; triceps, subscapular, and anterior thigh skinfolds; and subcutaneous fat layer were obtained on ten infants of diabetic mothers and ten infants of nondiabetic mothers. Measurements were taken at 48 h, 2 weeks, and 1 month postpartum. Maternal dietary intakes were recorded for 6 days during the third trimester of pregnancy. Infants of diabetic mothers and infants of nondiabetic mothers exhibited differences in birth length, 2-week and 1-month head circumference, 2-week triceps skinfold thickness, and fat layer. However, measurements differing at birth were not consistant with those differing at repeated measurements throughout the first month of life. Only the dietary intake of linoleic acid as a percentage of energy intake differed between the two groups of women. The diabetic women consumed more linoleic acid. The fat consumption pattern in the pregnant diabetic was unrelated to the subsequent anthropometric measurements of her infant. The well-controlled diabetics in this study did not have large-for-gestational-age infants.

Increased insulin binding to adipocytes and monocytes and increased insulin sensitivity of glucose transport and metabolism in adipocytes from non-insulin-dependent diabetics after a low-fat/high-starch/high-fiber diet

Nine non-insulin-dependent diabetics were studied before and after 3 weeks on an isoenergetic high-fiber/high-starch/low-fat diet (alternative diet), and nine non-insulin-dependent diabetics were studied on their usual diet. In the group that ate the alternative diet, the intake of fiber and starch increased 120% and 53%, whereas fat intake decreased 31%. Diabetes control improved as demonstrated by decreased fasting plasma glucose (P less than 0.05) and 24-hour urinary glucose excretion (P less than 0.05). The in vivo insulin action increased (KIVITT increased, P less than 0.05) with no change in fasting serum insulin levels. In fat cells obtained from patients in the alternative-diet group, insulin receptor binding increased (P less than 0.05) after the change of diet. Insulin binding to purified monocytes (more than 95% monocytes) also increased (P less than 0.05), whereas no change was found in insulin binding to erythrocytes. When lipogenesis was studied at a tracer glucose concentration at which glucose transport seems to be rate limiting, insulin sensitivity increased (P less than 0.02). This is the predicted consequence of increased receptor binding. Moreover, when CO2 production and lipogenesis were studied at a higher glucose concentration, where steps beyond transport seem to be rate limiting for glucose metabolism, increased insulin sensitivity was also observed. In contrast, no change was found in maximal insulin responsiveness. Fat and blood cells from the patients who continued on their usual diet showed no changes of the mentioned quantities.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved carbohydrate tolerance and stimulation of carbohydrate oxidation and lipogenesis during short-term carbohydrate overfeeding

The carbohydrate intake of seven healthy men was increased from 220-265 g/d to 620-770 g/d for 17 days, while protein and fat intake remained constant. Carbohydrate loading did not affect the preprandial plasma glucose levels after an overnight fast, but reduced the postprandial increment in plasma glucose levels after 5, 11, and 17 days of overfeeding. Preprandial plasma insulin levels were slightly increased during carbohydrate overfeeding, but no increase in the postprandial rise in insulin levels was found until 11 days after the start of carbohydrate loading. Whole-body rates of carbohydrate oxidation and of glucose conversion to fat were estimated by indirect calorimetry. Basal carbohydrate oxidation rate was increased by 95% at the end of 17 days of overfeeding, but there was no potentiation in the stimulation of the carbohydrate oxidation rate induced by a meal. There was no net fat synthesis from glucose before carbohydrate loading; carbohydrate overfeeding produced nonprotein respiratory exchange ratios greater than 1.00, suggesting net fat synthesis from glucose. Meals did not stimulate net lipogenesis from glucose, either before or after overfeeding. These results indicate that the improvement in carbohydrate tolerance associated with short-term carbohydrate loading does not appear to depend on elevated insulin levels. Increased carbohydrate oxidation and lipogenesis elevated carbohydrate disposal is more than necessary to account for the improvement in carbohydrate tolerance.

The nutritional therapy of non-insulin dependent (type II) diabetes

Confusion in the dietary manage ment of diabetes often arises from the lack of distinction between the two main types of diabetes and the dra matic difference in their dietary man agement. For obese Type II (NIDDM) diabetic individuals the achievement and maintenance of a desirable body weight is the primary nutritional goal of therapy. Other goals include achieving euglycemia and attempting to minimize the vascular manifesta tions of diabetes by correcting lipid ab normalities. Goals and nutritional strategies must be clearly understood so that concepts can be applied indi vidually. The optimal nutrient content of a diabetic diet (C, P, F) cannot yet be precisely defined and may be differ ent for different individuals. Dietary fiber may help to lower the blood glu cose and lipids, and natural foods con taining unrefined carbohydrates and fiber are recommended. Many nutri tive and non-nutritive sweeteners are on the market and, with some appro priate restrictions, can be used. With continual research and the emergence of new facts, it is inevitable that nutri tional recommendations will change.

Postprandial glucose and insulin responses to meals containing different carbohydrates in normal and diabetic subjects

To examine whether the form of dietary carbohydrate influences glucose and insulin responses, we studied the glucose and insulin responses to five meals--each containing a different form of carbohydrate but all with nearly identical amounts of total carbohydrate, protein, and fat--in 10 healthy subjects, 12 patients with Type I diabetes, and 10 patients with Type II diabetes. The test carbohydrates were glucose, fructose, sucrose, potato starch, and wheat starch. In all three groups, the meal containing sucrose as the test carbohydrate did not produce significantly greater peak increments in the plasma concentration of glucose or greater increments in the area under the plasma glucose-response curves than did meals containing potato, wheat, or glucose as test carbohydrates. Urinary excretion of glucose in patients with diabetes was not significantly greater after the sucrose meal. The meal containing fructose as the test carbohydrate produced the smallest increments in plasma glucose levels, but the differences were not always statistically significant. In healthy subjects and patients with Type II diabetes, peak serum concentrations of insulin were not significantly different in response to the five test carbohydrates. Our data do not support the view that dietary sucrose, when consumed as part of a meal, aggravates postprandial hyperglycemia.

Utilization of dietary cereal by young infants

The direct demonstration of cereal utilization by 16 healthy 1-month-old infants was achieved by tracing the appearance in breath CO2 of carbon derived from the fed cereal. These oxidation rates were compared with rates obtained from the feeding of glucose and glucose polymers. Fermentation of unabsorbed carbohydrate by the colonic flora was assessed by measurement of breath H2. Stools from four infants were analyzed for the quantity of carbon that originated from the cereal. Oxidation rates were not significantly different (mean = 31.2% of the dose fed). Mean peak hydrogen production was 39.8, 29.1, and 18.6 ppm for cereal, glucose polymers, and glucose, respectively. Cereal carbon was detected in the stools of two infants (3.7% and 13.1% of the ingested load). We conclude that young infants can utilize cereal, although absorption is not always complete. Hydrogen production increases with carbohydrate complexity; participation of colonic bacterial fermentation increases the net absorption of cereal.

Blood glucose and plasma insulin responses to various carbohydrates in type 2 (non-insulin-dependent) diabetes

The blood glucose and plasma insulin responses to some simple carbohydrates (glucose, fructose, lactose) and some complex ones (apples, potatoes, bread, rice, carrots and honey) were studied in 32 Type 2 (non-insulin-dependent) diabetic patients. Blood glucose and plasma insulin were measured at zero time and then at 15, 30, 60, 90 and 120 min after ingestion of 25 g glucose, fructose or lactose, or 30 g honey, 50 g white bread, 125 g white rice or potatoes, 150 g apples or 260 g carrots. Maximum blood glucose and plasma insulin responses were recorded 60 min after ingestion of each test meal. At this time the increases in blood glucose and in plasma insulin were significantly higher after the more refined carbohydrates (glucose, fructose and lactose) than after the more complex ones (apples, potatoes, rice, carrots and honey, -p less than 0.01). Counting the blood glucose increase after glucose as 100%, the corresponding increases in glycaemia for other carbohydrates were: fructose, 81.3%; lactose, 68.6%; apples, 46.9%; potatoes, 41.4%; bread, 36.3%; rice, 33.8%; honey, 32.4% and carrots, 16.1%.

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

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.