Dose-dependent effects of insoluble fibre on glucose metabolism: a stratified post hoc analysis of the Optimal Fibre Trial (OptiFiT)

High-protein vegan and omnivorous diets improve peripheral insulin sensitivity to a similar extent in people with type 2 diabetes

BACKGROUND

High-protein diets have been recognized as a potential strategy in the nutritional management of type 2 diabetes (T2D). Mycoprotein is a high-fibre, high-protein food ingredient previously shown to improve acute glycaemic control. We determined whether incorporating mycoprotein into a high-protein vegan diet would improve glycaemic control to a greater extent than an isonitrogenous omnivorous diet in people with T2D.

METHODS

Seventeen adults (f = 5, age = 58.3 ± 8.3 years, BMI = 32.9 ± 4.7 kg∙m-2, HbA1c = 60 ± 15 mmol∙mol-1) with T2D were randomly allocated to a 5-week eucaloric high-protein (30% energy from protein) diet, either an omnivorous diet (OMNI; 70% protein from omnivorous sources) or an isonitrogenous, mycoprotein-rich, vegan diet (VEG; 50% protein from mycoprotein). Glycaemic control was assessed using a two-step hyperinsulinaemic-euglycaemic clamp (HEC) with D-[6,6-2H2] glucose infusion, a mixed-meal tolerance test (MMTT) and continuous glucose monitoring.

RESULTS

The rate of glucose disappearance (RdT), glucose disposal rate and endogenous glucose production, as well as postprandial time-course of blood glucose, serum insulin and C-peptide were assessed during the HEC and MMTT, respectively. Both groups had improved peripheral insulin sensitivity (intervention effect, p = 0.006; increased RdT/Insulin of 1.0 ± 0.6 and 1.0 ± 0.3 mg kg-1 min-1 in OMNI and VEG, respectively), HbA1c (intervention; p = 0.001) and glycaemic variability (intervention; p = 0.040; increased time in-range of 11.8 ± 9.3% and 23.3 ± 12.9% in OMNI and VEG). There were no improvements in hepatic insulin sensitivity or in postprandial blood glucose and serum C-peptide (p > 0.05) during the MMTT.

CONCLUSIONS

High-protein diets, whether predicated on vegan or omnivorous proteins, can improve glycaemic control by increasing peripheral insulin sensitivity in people with T2D.

Predictive models of post-prandial glucose response in persons with prediabetes and early onset type 2 diabetes: A pilot study

OBJECTIVE

Post-prandial glucose response (PPGR) is a risk factor for cardiovascular disease. Meal carbohydrate content is an important predictor of PPGR, but dietary interventions to mitigate PPGR are not always successful. A personalized approach, considering behaviour and habitual pattern of glucose excursions assessed by continuous glucose monitor (CGM), may be more effective.

RESEARCH DESIGN AND METHODS

Data were collected under free-living conditions, over 2 weeks, in older adults (age 60 ± 7, BMI 33.0 ± 6.6 kg/m2), with prediabetes (n = 35) or early onset type 2 diabetes (n = 3), together with sleep and physical activity by actigraphy. We assessed the predictive value of habitual CGM glucose excursions and fasting glucose on PPGR after a research meal (hereafter MEAL-PPGR) and during an oral glucose tolerance test (hereafter OGTT-PPGR).

RESULTS

Mean amplitude of glucose excursions (MAGE) and fasting glucose were highly predictive of all measures of OGTT-PPGR (AUC, peak, delta, mean glucose and glucose at 120 min; R2 between 0.616 and 0.786). Measures of insulin sensitivity and β-cell function (Matsuda index, HOMA-B and HOMA-IR) strengthened the prediction of fasting glucose and MAGE (R2 range 0.651 to 0.832). Similarly, MAGE and premeal glucose were also strong predictors of MEAL-PPGR (R2 range 0.546 to 0.722). Meal carbohydrates strengthened the prediction of 3 h AUC (R2 increase from 0.723 to 0.761). Neither anthropometrics, age nor habitual sleep and physical activity added to the prediction models significantly.

CONCLUSION

These data support a CGM-guided personalized nutrition and medicine approach to control PPGR in older individuals with prediabetes and diet and/or metformin-treated type 2 diabetes.

Postprandial hyperglycemia in patients with type 2 diabetes is reduced by raw insoluble fiber: A randomized trial

BACKGROUND AND AIMS

A lower risk of type 2 diabetes mellitus (T2DM) is associated with the intake of insoluble fiber. This contradicts the postulate that insoluble fibers do not decrease postprandial glycemic response and that only viscous gel-forming soluble fibers would do this. This study aimed to investigate the effect of a dose of insoluble fibers that meets dietary recommendations on postprandial hyperglycemia in T2DM patients.

METHODS AND RESULTS

This is a randomized crossover clinical trial. Nineteen T2DM men randomly ate a balanced breakfast either without (Control) or with prior consumption of insoluble fibers (5.8 g) in the form of 15 g of raw wheat bran (RWB). Glycemia was measured at fasting and 15, 30, 45, 60, 90, and 120 min postprandially. Markers of taste intensity and palatability were assessed after breakfast intake. The glucose peak rise of 87 mg/dL and the incremental area under the curve (AUC) elicited by the breakfast were decreased by RWB (15.80 % and 23.14 %, respectively). Time-to-glucose-peak did not differ between groups. The addition of the RWB to the meal decreased its level of creaminess and tasty and increased the sourness and bitterness.

CONCLUSIONS

The postprandial hyperglycemia in T2DM patients in response to complex carbohydrates was decreased by prior intake of a recommended dose of raw insoluble fibers. This antihyperglycemic effect is in accordance with the acarbose-like property of raw insoluble fibres, but not of heated ones (e.g., bread and pasta), to inhibit the activities of the carbohydrate-digesting enzymes alpha-glucosidase/alpha-amylase.

REGISTRATION NUMBER FOR CLINICAL TRIALS

RBR-98tx28b (https://ensaiosclinicos.gov.br/rg/RBR-98tx28b).

Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial

INTRODUCTION

Contradictory claims about the efficacy of several medicinal plants to promote glycemic control in patients with type 2 diabetes mellitus (T2DM) have been explained by divergences in the administration form and by extrapolation of data obtained from healthy individuals. It is not known whether the antidiabetic effects of traditional herbal medicines are influenced by gelatin capsules. This randomized crossover trial aimed to evaluate the acute effect of a single dose of raw cinnamon consumed orally either dissolved in water as a beverage or as ordinary hard gelatin capsules on postprandial hyperglycemia (>140 mg/dL; >7.8 mmol/L) in T2DM patients elicited by a nutritionally-balanced meal providing 50 g of complex carbohydrates.

METHODS

Fasting T2DM patients (n = 19) randomly ingested a standardized meal in five experimental sessions, one alone (Control) and the other after prior intake of 3 or 6 g of crude cinnamon in the form of hard gelatin capsules or powder dissolved in water. Blood glucose was measured at fasting and at 0.25, 0.5, 0.75, 1, 1.5 and 2 hours postprandially. After each breakfast, its palatability scores for visual appeal, smell and pleasantness of taste were assessed, as well as the taste intensity sweetness, saltiness, bitterness, sourness and creaminess.

RESULTS

The intake of raw cinnamon dissolved in water, independently of the dose, decreased the meal-induced large glucose spike (peak-rise of +87 mg/dL and Δ1-hour glycemia of +79 mg/dL) and the hyperglycemic blood glucose peak. When cinnamon was taken as capsules, these anti-hyperglycemic effects were lost or significantly diminished. Raw cinnamon intake did not change time-to-peak or the 2-h post-meal glycaemia, but flattened the glycemic curve (lower iAUC) without changing the shape that is typical of T2DM patients.

CONCLUSIONS

This cinnamon's antihyperglycemic action confirms its acarbose-like property to inhibit the activities of the carbohydrate-digesting enzymes α-amylases/α-glucosidases, which is in accordance with its exceptionally high content of raw insoluble fiber. The efficacy of using raw cinnamon as a diabetes treatment strategy seems to require its intake at a specific time before/concomitantly the main hyperglycemic daily meals. Trial registration: Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-98tx28b.

Dietary Fibre for the Prevention of Post-Pancreatitis Diabetes Mellitus: A Review of the Literature and Future Research Directions

Post-pancreatitis diabetes mellitus-the most common sequela of pancreatitis-leads to poorer glycaemic control compared with type 2 diabetes. Because post-pancreatitis diabetes mellitus is an exemplar of secondary diabetes (with a clear underlying cause), much post-pancreatitis diabetes mellitus is preventable or treatable early. Earlier literature established the important role of dietary fibre in reducing plasma glucose in individuals with type 2 diabetes. The present review benchmarks available evidence on the role of habitual dietary fibre intake in pancreatitis and post-pancreatitis diabetes mellitus. It also paves the way for future research on the use of dietary fibre in the post-pancreatitis setting.

Acute Flaxseed Intake Reduces Postprandial Glycemia in Subjects with Type 2 Diabetes: A Randomized Crossover Clinical Trial

Background: Postprandial glycemic excursions are associated with impairment control of diabetes mellitus. Long-term consumption of flaxseed can lower blood glucose levels; however, its effects on the postprandial glycemic response remain unknown. Therefore, this study aimed to evaluate the acute effects of raw flaxseed consumption on the 2 h postprandial glycemic curve in men with type 2 diabetes mellitus (T2DM). Methods: This was a randomized crossover clinical trial. Nineteen men with T2DM were randomly assigned a standardized breakfast without (control) or with a previous intake of 15 g of ground raw golden flaxseed (flax). Glycemia was measured at fasting and postprandial at 15, 30, 45, 60, 90, and 120 min. Palatability markers (visual appeal, smell, and pleasantness of taste) and taste intensity (sweetness, saltiness, bitterness, sourness, and creaminess) were evaluated. Results: The peak glucose rise and the 2 h AUC glycemic response reduced in the flax group by 17% (p = 0.001) and 24% (p < 0.001), respectively. The glucose peak time, palatability, and taste parameters did not differ between the two groups. Conclusions: Ingestion of 15 g of ground raw golden flaxseed before breakfast decreases the 2 h postprandial glycemic response in men with T2DM.