Perturbations of the composition and function of the gut microbiota have been associated with metabolic disorders including obesity, insulin resistance and type 2 diabetes. Studies on mice have demonstrated several underlying mechanisms including host signalling through bacterial lipopolysaccharides derived from the outer membranes of Gram-negative bacteria, bacterial fermentation of dietary fibres to short-chain fatty acids and bacterial modulation of bile acids. On top of this, an increased permeability of the intestinal epithelium may lead to increased absorption of macromolecules from the intestinal content resulting in systemic immune responses, low-grade inflammation and altered signalling pathways influencing lipid and glucose metabolism. While mechanistic studies on mice collectively support a causal role of the gut microbiota in metabolic diseases, the majority of studies in humans are correlative of nature and thus hinder causal inferences. Importantly, several factors known to influence the risk of type 2 diabetes, e.g. diet and age, have also been linked to alterations in the gut microbiota complicating the interpretation of correlative studies. However, based upon the available evidence, it is hypothesised that the gut microbiota may mediate or modulate the influence of lifestyle factors triggering development of type 2 diabetes. Thus, the aim of this review is to critically discuss the potential role of the gut microbiota in the pathophysiology and pathogenesis of type 2 diabetes.
Cardiovascular morbidity is a major burden in patients with type 2 diabetes. In the Steno-2 Study, we compared the effect of a targeted, intensified, multifactorial intervention with that of conventional treatment on modifiable risk factors for cardiovascular disease in patients with type 2 diabetes and microalbuminuria.The primary end point of this open, parallel trial was a composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, revascularization, and amputation. Eighty patients were randomly assigned to receive conventional treatment in accordance with national guidelines and 80 to receive intensive treatment, with a stepwise implementation of behavior modification and pharmacologic therapy that targeted hyperglycemia, hypertension, dyslipidemia, and microalbuminuria, along with secondary prevention of cardiovascular disease with aspirin.The mean age of the patients was 55.1 years, and the mean follow-up was 7.8 years. The decline in glycosylated hemoglobin values, systolic and diastolic blood pressure, serum cholesterol and triglyceride levels measured after an overnight fast, and urinary albumin excretion rate were all significantly greater in the intensive-therapy group than in the conventional-therapy group. Patients receiving intensive therapy also had a significantly lower risk of cardiovascular disease (hazard ratio, 0.47; 95 percent confidence interval, 0.24 to 0.73), nephropathy (hazard ratio, 0.39; 95 percent confidence interval, 0.17 to 0.87), retinopathy (hazard ratio, 0.42; 95 percent confidence interval, 0.21 to 0.86), and autonomic neuropathy (hazard ratio, 0.37; 95 percent confidence interval, 0.18 to 0.79).A target-driven, long-term, intensified intervention aimed at multiple risk factors in patients with type 2 diabetes and microalbuminuria reduces the risk of cardiovascular and microvascular events by about 50 percent.
Abstract Genome-wide association studies (GWAS) have identified more than 80 susceptibility loci for type 2 diabetes (T2D), but most of its heritability still remains to be elucidated. In this study, we conducted a meta-analysis of GWAS for T2D in the Japanese population. Combined data from discovery and subsequent validation analyses (23,399 T2D cases and 31,722 controls) identify 7 new loci with genome-wide significance ( P <5 × 10 −8 ), rs1116357 near CCDC85A , rs147538848 in FAM60A , rs1575972 near DMRTA1 , rs9309245 near ASB3 , rs67156297 near ATP8B2 , rs7107784 near MIR4686 and rs67839313 near INAFM2 . Of these, the association of 4 loci with T2D is replicated in multi-ethnic populations other than Japanese (up to 65,936 T2Ds and 158,030 controls, P <0.007). These results indicate that expansion of single ethnic GWAS is still useful to identify novel susceptibility loci to complex traits not only for ethnicity-specific loci but also for common loci across different ethnicities.
<p> </p> <p><strong>Objective</strong></p> <p>The association between <em>FTO</em> rs9939609 and obesity is modified by physical activity (PA) and/or insulin sensitivity (IS). We aimed to assess whether these modifications are independent, if PA and/or IS modify the association between rs9939609 and cardiometabolic traits, and to elucidate underlying mechanisms.</p> <p><strong>Research Design and Methods</strong></p> <p>Genetic association analyses comprised up to 19,585 individuals. PA was self-reported and IS was defined based on inverted HOMA-IR. Functional analyses were performed in muscle biopsies from 140 men, and in cultured muscle cells.</p> <p><strong>Results</strong></p> <p>The BMI-increasing effect of the <em>FTO</em> rs9939609 A-allele was attenuated by 47% with high PA (β (standard error (SE)), -0.32 (0.10) kg/m2, p=0.0013), and by 51% with high IS (-0.31 (0.09) kg/m2, p=0.00028). Interestingly, these interactions were essentially independent (PA, -0.20 (0.09) kg/m2, p=0.023; IS, -0.28 (0.09) kg/m2, p=0.0011). The rs9939609 A-allele was also associated with higher all-cause mortality and certain cardiometabolic outcomes (hazard ratio, 1.07-1.20, p>0.04), and these effects tended to be weakened by greater PA and IS. Moreover, the rs9939609 A-allele was associated with higher expression of <em>FTO </em>in skeletal muscle tissue (0.03 (0.01), p=0.011), and in skeletal muscle cells, we identified a physical interaction between the <em>FTO</em> promoter and an enhancer region encompassing rs9939609. </p> <p><strong>Conclusions </strong></p> <p>Greater PA and IS independently reduced the effect of rs9939609 on obesity. These effects might be mediated through altered expression of <em>FTO</em> in skeletal muscle. Our results indicated that PA and/or other means of increasing insulin sensitivity could counteract <em>FTO</em>–related genetic predisposition to obesity.</p>
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
