Higher intake of microbiota-accessible carbohydrates and improved cardiometabolic risk factors: a meta-analysis and umbrella review of dietary management in patients with type 2 diabetes

Abstract

Background Microbiota-accessible carbohydrates (MACs) are critical substrates for intestinal microbes; the subsequent production of SCFAs may have some potential benefits for patients with type 2 diabetes mellitus (T2DM). Objectives We conducted a meta-analysis of randomized controlled trials (RCTs) to assess the effects of higher compared with lower MAC intakes on cardiovascular risk factors in T2DM patients and performed an umbrella review of RCTs to evaluate the evidence quality concerning existing dietary T2DM interventions. Methods Publications were identified by searching MEDLINE, EMBASE, and CINAHL. In the meta-analysis, random-effects models were used to calculate pooled estimates, and sensitivity analyses, meta-regression, subgroup analyses, and Egger's test were performed. For the umbrella review, we summarized pooled estimates, 95% CIs, heterogeneity, and publication bias. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) and modified NutriGrade were used to assess the quality of evidence in the meta-analysis and umbrella review, respectively. Results Forty-five RCTs with 1995 participants were included in the meta-analysis. High MAC intake significantly reduced glycated hemoglobin (HbA1c) (weighted mean difference [WMD] –0.436% [–0.556, –0.315]), fasting glucose (WMD –0.835 mmol/L [–1.048, –0.622]), total cholesterol (WMD –0.293 mmol/L [–0.397, –0.190]), triglycerides (WMD –0.118 mmol/L [–0.308, –0.058]), BMI (WMD –0.476 [–0.641, –0.312]), and systolic blood pressure (WMD –3.066 mmHg [–5.653, –0.478]), with a moderate-to-high quality of evidence, compared with low intake. Region, dose, and MAC type were key variables. The umbrella review of all dietary interventions for cardiovascular risk factors in patients with T2DM included 26 meta-analyses with 158 pooled estimates. The evidence quality of MACs, dietary fiber, high-protein diet, ω-3 (n–3), viscous fiber, vitamin D, and vitamin E intake was moderate to high. Conclusions When compared with lower intake, increased MAC intake improved glycemic control, blood lipid, body weight, and inflammatory markers for people with T2DM. This trial was registered at PROSPERO (https://www.crd.york.ac.uk/PROSPERO/#recordDetails) as CRD42019120531.

Empfehlungen zur Ernährung von Personen mit Typ-2-Diabetes mellitus

“…Bei Patienten mit T2Dm kann ein starker Verzehr von Lebensmitteln mit einem niedrigen GI wie Hülsenfrüchten und Hafer die Blutzuckereinstellung verbessern, die Insulinsensitivität steigern und damit den Insulinbedarf senken [165]. Diese Effekte werden heute anteilig über einen positiven Einfluss von schwer verdaulichen Kohlenhydraten auf das Mikrobiom erklärt [166]. Bis heute bleibt strittig, inwieweit der Nutzen einer Low-GI-Diät durch deren höheren Ballaststoffgehalt erklärt ist.…”

Possibility of Venous Serum Cl− Concentration ([Cl−]s) as a Marker for Human Metabolic Status: Correlation of [Cl−]s to Age, Fasting Blood Sugar (FBS), and Glycated Hemoglobin (HbA1c)

“…To exactly detect the metabolic condition, we have to measure various factors such as O 2 consumption, CO 2 production, pH in venous serum, HCO 3 − concentration in venous serum ([HCO 3 − ] s ), fasting blood sugar (FBS), and glycated hemoglobin (HbA1c), etc. [1][2][3][4]. However, even though O 2 consumption and CO 2 production are measured, certain momentary values of O 2 consumption and CO 2 production are not enough to estimate the metabolic condition of whole body, but continuous measurements of O 2 consumption and CO 2 production are required to detect the relatively chronic metabolic condition of whole body [1][2][3][4].…”

“…[1][2][3][4]. However, even though O 2 consumption and CO 2 production are measured, certain momentary values of O 2 consumption and CO 2 production are not enough to estimate the metabolic condition of whole body, but continuous measurements of O 2 consumption and CO 2 production are required to detect the relatively chronic metabolic condition of whole body [1][2][3][4]. On the one hand, concentrations of electrolytes such as H + and HCO 3 − in the venous serum show the relatively chronic status of metabolic conditions [5][6][7][8][9], although acute changes in metabolic conditions would also affect H + and HCO 3 − concentrations in the venous serum with a time lag dependent on the degree and the time duration of the acute metabolic changes.…”

“…Even though these measurements could provide crucial information on the metabolic status, these measurements require technically complicated processes. On the other hand, to obtain information on metabolic conditions of huge numbers of 2 of 19 persons taking only basic medical examinations not including [HCO 3 − ] s measurements, we should find out another index measurable using a technique easily adaptable to huge numbers of persons. Here, we considered that the venous serum Cl − concentration ([Cl − ] s ) could be an index indicating metabolic conditions, since Cl − is an easily measurable index and [Cl − ] s changes to the opposite direction with the change in [HCO 3 − ] s .…”

“…Here, we considered that the venous serum Cl − concentration ([Cl − ] s ) could be an index indicating metabolic conditions, since Cl − is an easily measurable index and [Cl − ] s changes to the opposite direction with the change in [HCO 3 − ] s . We assumed that the total amount of [Cl − ] s and [HCO 3 − ] s would be approximately constant, as described as follows. The source of HCO 3 − is CO 2 produced in metabolic cells such as myocytes, hepatocytes, and renal epithelial cells, moving into erythrocytes [6,10].…”