The proportion of daily energy provided by carbohydrate intake is not an important determinant of response to dietary management, especially when considering longer term trials. A range of dietary patterns, including those traditional in Mediterranean countries, seems suitable for translating nutritional recommendations for individuals with diabetes into practical advice.

Purpose Compared to a healthy population, the gut microbiota in type 2 diabetes presents with several unfavourable features that may impair glucose regulation. The aim of this study was to evaluate the prebiotic effect of inulin-type fructans on the faecal microbiota and short-chain fatty acids (SCFA) in patients with type 2 diabetes. Methods The study was a placebo controlled crossover study, where 25 patients (15 men) aged 41–71 years consumed 16 g of inulin-type fructans (a mixture of oligofructose and inulin) and 16-g placebo (maltodextrin) for 6 weeks in randomised order. A 4-week washout separated the 6 weeks treatments. The faecal microbiota was analysed by high-throughput 16S rRNA amplicon sequencing and SCFA in faeces were analysed using vacuum distillation followed by gas chromatography. Results Treatment with inulin-type fructans induced moderate changes in the faecal microbiota composition (1.5%, p = 0.045). A bifidogenic effect was most prominent, with highest positive effect on operational taxonomic units (OTUs) of Bifidobacterium adolescentis, followed by OTUs of Bacteroides. Significantly higher faecal concentrations of total SCFA, acetic acid and propionic acid were detected after prebiotic consumption compared to placebo. The prebiotic fibre had no effects on the concentration of butyric acid or on the overall microbial diversity. Conclusion Six weeks supplementation with inulin-type fructans had a significant bifidogenic effect and induced increased concentrations of faecal SCFA, without changing faecal microbial diversity. Our findings suggest a moderate potential of inulin-type fructans to improve gut microbiota composition and to increase microbial fermentation in type 2 diabetes. Trial registration The trial is registered at clinicaltrials.gov (NCT02569684).

The recommended amount and quality of protein in diets of diabetic patients are highly controversial. In order to provide evidence-based information, the Diabetes Nutrition Study Group (DNSG) used a grading procedure used for quality of evidence and strength of recommendations (GRADE). A protein intake of 10% to 20% of energy intake (E%) or about 0.8 to 1.3 g/kg body weight in people below 65 years of age, and 15% to 20% of E% in people above 65 years of age appeared safe in weight-stable conditions. There were no intervention studies addressing metabolic effects, mortality, or cardiovascular events over prolonged periods. Body weight is closely linked to metabolic control and high protein diets are often recommended. Weight-loss diets that include 23% to 32% of E% as protein for up to one year reduced blood pressure and body weight slightly but significantly more than lower protein diets, whereas blood lipids, fasting blood glucose, and HbA1c improved similarly with higher or lower protein intakes in participants with a glomerular filtration rate (GFR) >60 mL/min/1.73 m2. Patients with a GFR <60 mL/min/1.73 m2 did not show a faster decline of GFR or kidney function with protein intakes around 0.8 g/kg body weight as compared with lower intakes, thereby arguing against a restriction. The effects of protein intake on diabetic eye or nerve disease have not been reported. There are a number of studies that have compared different types of animal proteins (milk, chicken, beef, pork, and fish) or compared animal with plant protein in diabetic patients and have reported a greater reduction of serum cholesterol with plant protein. In summary, the suggested range of protein intake appears to be safe and can be adapted according to personal dietary preferences.

Background Weight regain after bariatric surgery often starts after 1-2 y, but studies evaluating strategies to prevent weight regain are lacking. The aim of this intervention was to evaluate the efficacy of a 2-y-group-based lifestyle intervention starting approximately 2 y after Roux-en-Y gastric bypass (RYGB) compared with usual care on weight regain and related metabolic risk factors. Methods A total of 165 patients with a mean of 21 months (range 14-32) after RYGB were randomized to a lifestyle intervention group (LIG) or a usual care group (UCG). Of the 165 participants 86% completed the study. The LIG was offered 16 group meetings over 2 y with focus on healthy diet, physical activity, and behavioural strategies to prevent weight regain, in addition to usual care. Results Mean (SD) total weight loss at study start was 30.1 ± 8.2%, while weight regain during the intervention was 4.9 ± 7.4 and 4.6 ± 9.2% in the LIG and UCG, respectively (P = 0.84). There were no differences in metabolic risk factors between the groups. The LIG participants attended 8 ± 4 group meetings, with no difference in weight regain between participants with high compared to lower participation. In all the participants, a positive association between weight increase from nadir to study start and weight regain during the intervention was found. Participants who reported physical activity ≥ 150 min/wk had smaller % weight regain compared with less active participants (β = − 5.2 [SE 2.0, 95% CI − 9.1 to − 1.4]). Conclusion We found no difference in weight regain between LIG and UCG.

Dietary fibre is a generic term describing non-absorbed plant carbohydrates and small amounts of associated non-carbohydrate components. The main contributors of fibre to the diet are the cell walls of plant tissues, which are supramolecular polymer networks containing variable proportions of cellulose, hemicelluloses, pectic substances, and non-carbohydrate components, such as lignin. Other contributors of fibre are the intracellular storage oligosaccharides, such as fructans. A distinction needs to be made between intrinsic sources of dietary fibre and purified forms of fibre, given that the three-dimensional matrix of the plant cell wall confers benefits beyond fibre isolates. Movement through the digestive tract modifies the cell wall structure and may affect the interactions with the colonic microbes (e.g., small intestinally non-absorbed carbohydrates are broken down by bacteria to short-chain fatty acids, absorbed by colonocytes). These aspects, combined with the fibre associated components (e.g., micronutrients, polyphenols, phytosterols, and phytoestrogens), may contribute to the health outcomes seen with the consumption of dietary fibre. Therefore, where possible, processing should minimise the degradation of the plant cell wall structures to preserve some of its benefits. Food labelling should include dietary fibre values and distinguish between intrinsic and added fibre. Labelling may also help achieve the recommended intake of 14 g/1000 kcal/day.

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Plasma AAAs, BCAAs, and tCys at 2 years were associated with BMI at 2 years. In addition, plasma AAAs and BCAAs at 2 years were associated with weight loss from 0 to 2 years, while tCys at 2 years was associated with weight regain from 2 to 4 years after RYGB. These results suggest that high tCys at 2 years may be used as a prognostic marker for future weight regain. The study was registered in ClinicalTrials.gov (NCT0 1270451).