A carbohydrate-reduced high-protein diet acutely decreases postprandial and diurnal glucose excursions in type 2 diabetes patients

Abstract

The aim of the study was to assess whether a simple substitution of carbohydrate in the conventionally recommended diet with protein and fat would result in a clinically meaningful reduction in postprandial hyperglycaemia in subjects with type 2 diabetes mellitus (T2DM). In all, sixteen subjects with T2DM treated with metformin only, fourteen male, with a median age of 65 (43-70) years, HbA1c of 6·5 % (47 mmol/l) (5·5-8·3 % (37-67 mmol/l)) and a BMI of 30 (sd 4·4) kg/m2 participated in the randomised, cross-over study. A carbohydrate-reduced high-protein (CRHP) diet was compared with an iso-energetic conventional diabetes (CD) diet. Macronutrient contents of the CRHP/CD diets consisted of 31/54 % energy from carbohydrate, 29/16 % energy from protein and 40/30 % energy from fat, respectively. Each diet was consumed on 2 consecutive days in a randomised order. Postprandial glycaemia, pancreatic and gut hormones, as well as satiety, were evaluated at breakfast and lunch. Compared with the CD diet, the CRHP diet reduced postprandial AUC of glucose by 14 %, insulin by 22 % and glucose-dependent insulinotropic polypeptide by 17 % (all P<0·001), respectively. Correspondingly, glucagon AUC increased by 33 % (P<0·001), cholecystokinin by 24 % (P=0·004) and satiety scores by 7 % (P=0·035), respectively. A moderate reduction in carbohydrate with an increase in fat and protein in the diet, compared with an energy-matched CD diet, greatly reduced postprandial glucose excursions and resulted in increased satiety in patients with well-controlled T2DM.

James Lind Alliance research priorities: what role do carbohydrates, fats and proteins have in the management of Type 2 diabetes, and are there risks and benefits associated with particular approaches?

“…This hypothesis should be formally tested in a well‐designed trial. Since the publication of the two meta‐analyses, more randomized trials have reported . In general, their results are consistent with those of the meta‐analyses: a higher proportion of protein in the diet appears to have little effect on glycaemia independent of weight loss.…”

The incretin system in healthy humans: The role of GIP and GLP-1

“…This seems self-evident, but is nevertheless an important factor in the planning of diets for people with glucose intolerance. Only recently has it become generally accepted that low carbohydrate diets have a major beneficial effect on the course and risk of complications in patients with T2DM, with even moderate reductions resulting in significantly improved haemoglobin A1c levels and reduced liver fat (and thereby improved insulin sensitivity and increased insulin clearance) [6,7]. A related issue is the glycemic index of the ingested carbohydrates the lower the glycemic index, the lower the postprandial glucose levels, and again it is assumed that such reductions will reduce the cardiovascular risk [7].…”

Low and reduced carbohydrate diets: challenges and opportunities for type 2 diabetes management and prevention

“…The idea of LCDs for weight loss first attracted public interest with the letter of William Banting published in 1863 describing his successful personal weight loss of 46 lbs (~20 kg), from 202 lbs to 156 lbs over a 12-month period, by cutting bread, potato, pastry, milk, sugar, and a majority of fruits (63) . Several anecdotal reports of similar success have been discussed in the media (64)(65)(66) , highlighting that the successful weight loss stories with LCDs could be subject to survival bias, with the experience of those who tried and failed not being reported. LCDs can achieve a mean weight loss of 7 kg approximately over 6-24 months, up to 10% of baseline body weight in non-controlled studies (67)(68)(69)(70) .…”

“…LCDs have been postulated to have physiological benefits over higher carbohydrate diets for HbA1c reduction. A lower postprandial glucose excursion would be expected after LCDs, compared to higher carbohydrate diets if they present greater glycaemic index or glycaemic loads (66,101) . A reduced postprandial excursion should lead to a better overall glucose control and lower HbA1c.…”