Causality of small and large intestinal microbiota in weight regulation and insulin resistance

OBJECTIVE

The twin pandemics of obesity and Type 2 diabetes (T2D) are a global challenge for health care systems. Changes in the environment, behavior, diet, and lifestyle during the last decades are considered the major causes. A Western diet, which is rich in saturated fat and simple sugars, may lead to changes in gut microbial composition and physiology, which have recently been linked to the development of metabolic diseases.

METHODS

We will discuss evidence that demonstrates the influence of the small and large intestinal microbiota on weight regulation and the development of insulin resistance, based on literature search.

RESULTS

Altered large intestinal microbial composition may promote obesity by increasing energy harvest through specialized gut microbes. In both large and small intestine, microbial alterations may increase gut permeability that facilitates the translocation of whole bacteria or endotoxic bacterial components into metabolic active tissues. Moreover, changed microbial communities may affect the production of satiety-inducing signals. Finally, bacterial metabolic products, such as short chain fatty acids (SCFAs) and their relative ratios, may be causal in disturbed immune and metabolic signaling, notably in the small intestine where the surface is large. The function of these organs (adipose tissue, brain, liver, muscle, pancreas) may be disturbed by the induction of low-grade inflammation, contributing to insulin resistance.

CONCLUSIONS

Interventions aimed to restoring gut microbial homeostasis, such as ingestion of specific fibers or therapeutic microbes, are promising strategies to reduce insulin resistance and the related metabolic abnormalities in obesity, metabolic syndrome, and type 2 diabetes. This article is part of a special issue on microbiota.

Effect of liraglutide on physical performance in type 2 diabetes (LIPER2): A randomised, double-blind, controlled trial

Preclinical studies and small clinical trials suggest that glucagon-like peptide 1 (GLP1) may have a positive effect on ventricular function. Liraglutide is a GLP1-analogue used in the treatment of type 2 diabetes. LIPER2 is a phase IV, randomised, double-blind, placebo-controlled, parallel-design trial, assessing the effect of 6 months' liraglutide 1.8 mg/d on measures of cardiac function and physical performance in patients with type 2 diabetes. A total of 30 patients with type 2 diabetes will be included, if their HbA1c is between 7 and 10% while on oral agents (including metformin if tolerated and not contraindicated), a maximum of 2 intermediate or long-acting insulin injections per day or a combination of both. After their baseline examinations, patients are randomised to receive a daily subcutaneous liraglutide or placebo injection (titrated to 1.8 mg/d if tolerated) for 6 months. The primary end-point is the maximal oxygen consumption during cycle ergometry at the end of the study period. Other end-points include distance covered during a 6-min walk test, left ventricular ejection fraction and other measures of ventricular systolic and diastolic functions assessed by echocardiography, heart rate, blood pressure, pro-brain natriuretic peptide, C-reactive protein, HbA1c, lipids, apolipoprotein B, body weight and waist girth. Safety end-points include adverse event reporting, blood count, kidney and liver function, amylase, lipase, electrolytes, calcitonin, CA19.9 and pregnancy test for fertile women. At the time of this report, recruitment is still ongoing. Results are expected to be reported in December 2016.