Association of RPS26 gene polymorphism with different types of diabetes in Chinese individuals.

AIMS/INTRODUCTION: Different types of diabetes show distinct genetic characteristics, but the specific genetic susceptibility factors remain unclear. Our study aimed to explore the associations between the ribosomal protein S26 (RPS26) gene rs1131017 polymorphisms and susceptibility to type 1 diabetes mellitus, latent autoimmune diabetes in adults (LADA) and type 2 diabetes mellitus in the Chinese Han population, and their correlations with clinical features. MATERIALS AND METHODS: Genotyping of the rs1131017 variant was carried out for 1,006 type 1 diabetes mellitus patients, 210 LADA patients, 642 type 2 diabetes mellitus patients and 2,099 control individuals. RESULTS: We found that the rs1131017 C allele was a risk locus for both type 1 diabetes mellitus and LADA (odds ratio [OR] 1.50, 95% confidence interval [CI] 1.33-1.69, P < 0.001; OR 1.31, 95% CI 1.04-1.64, P = 0.021, respectively). Nevertheless, this association was not found for type 2 diabetes mellitus. Carrying the C allele genotype was associated with a lower postprandial C-peptide for type 1 diabetes mellitus (OR 1.41, 95% CI 1.11-1.80, P = 0.006) and lower fasting C-peptide for LADA (OR 1.55, 95% CI 1.01-2.38, P = 0.047). Interestingly, a lower GC frequency was noted for LADA than for type 1 diabetes mellitus, regardless of classification based on age at diagnosis, C-peptide or glutamic acid decarboxylase antibody positivity. CONCLUSIONS: The RPS26 polymorphism was associated with susceptibility and clinical characteristics of type 1 diabetes mellitus and LADA in the Chinese population, but was not related to type 2 diabetes mellitus. Thus, it might serve as a novel biomarker for particular types of diabetes.

Upregulated TGF-ß1 contributes to hyperglycaemia in type 2 diabetes by potentiating glucagon signalling.

AIMS/HYPOTHESIS: Glucagon-stimulated hepatic gluconeogenesis contributes to endogenous glucose production during fasting. Recent studies suggest that TGF-ß is able to promote hepatic gluconeogenesis in mice. However, the physiological relevance of serum TGF-ß levels to human glucose metabolism and the mechanism by which TGF-ß enhances gluconeogenesis remain largely unknown. As enhanced gluconeogenesis is a signature feature of type 2 diabetes, elucidating the molecular mechanisms underlying TGF-ß-promoted hepatic gluconeogenesis would allow us to better understand the process of normal glucose production and the pathophysiology of this process in type 2 diabetes. This study aimed to investigate the contribution of upregulated TGF-ß1 in human type 2 diabetes and the molecular mechanism underlying the action of TGF-ß1 in glucose metabolism. METHODS: Serum levels of TGF-ß1 were measured by ELISA in 74 control participants with normal glucose tolerance and 75 participants with type 2 diabetes. Human liver tissue was collected from participants without obesity and with or without type 2 diabetes for the measurement of TGF-ß1 and glucagon signalling. To investigate the role of Smad3, a key signalling molecule downstream of the TGF-ß1 receptor, in mediating the effect of TGF-ß1 on glucagon signalling, we generated Smad3 knockout mice. Glucose levels in Smad3 knockout mice were measured during prolonged fasting and a glucagon tolerance test. Mouse primary hepatocytes were isolated from Smad3 knockout and wild-type (WT) mice to investigate the underlying molecular mechanisms. Smad3 phosphorylation was detected by western blotting, levels of cAMP were detected by ELISA and levels of protein kinase A (PKA)/cAMP response element-binding protein (CREB) phosphorylation were detected by western blotting. The dissociation of PKA subunits was measured by immunoprecipitation. RESULTS: We observed higher levels of serum TGF-ß1 in participants without obesity and with type 2 diabetes than in healthy control participants, which was positively correlated with HbA1c and fasting blood glucose levels. In addition, hyperactivation of the CREB and Smad3 signalling pathways was observed in the liver of participants with type 2 diabetes. Treating WT mouse primary hepatocytes with TGF-ß1 greatly potentiated glucagon-stimulated PKA/CREB phosphorylation and hepatic gluconeogenesis. Mechanistically, TGF-ß1 treatment induced the binding of Smad3 to the regulatory subunit of PKA (PKA-R), which prevented the association of PKA-R with the catalytic subunit of PKA (PKA-C) and led to the potentiation of glucagon-stimulated PKA signalling and gluconeogenesis. CONCLUSIONS/INTERPRETATION: The hepatic TGF-ß1/Smad3 pathway sensitises the effect of glucagon/PKA signalling on gluconeogenesis and synergistically promotes hepatic glucose production. Reducing serum levels of TGF-ß1 and/or preventing hyperactivation of TGF-ß1 signalling could be a novel approach for alleviating hyperglycaemia in type 2 diabetes.

Latent Autoimmune Diabetes in Adults (LADA): From Immunopathogenesis to Immunotherapy.

Latent autoimmune diabetes in adults (LADA) is a type of diabetes characterized by slow autoimmune damage of pancreatic ß cells without insulin treatment in the early clinical stage. There are differences between LADA and classical type 1 diabetes (T1D) and type 2 diabetes (T2D) in genetic background, autoimmune response, rate of islet function decline, clinical metabolic characteristics, and so on. The disease progression and drug response of patients with LADA are closely related to the level of islet autoimmunity, thus exploring the pathogenesis of LADA is of great significance for its prevention and treatment. Previous studies reported that adaptive immunity and innate immunity play a critical role in the etiology of LADA. Recent studies have shown that the intestinal microbiota which impacts host immunity hugely, participates in the pathogenesis of LADA. In addition, the progression of autoimmune pancreatic ß cell destruction in LADA is slower than in classical T1D, providing a wider window of opportunities for intervention. Therefore, therapies including antidiabetic drugs with immune-regulation effects and immunomodulators could contribute to promising interventions for LADA. We also shed light on potential interventions targeting the gut microbiota and gut-associated immunity, which may be envisaged to halt or delay the process of autoimmunity in LADA.

Sodium-glucose cotransporter inhibitors as add-on therapy in addition to insulin for type 1 diabetes mellitus: A meta-analysis of randomized controlled trials.

AIMS/INTRODUCTION: Several clinical trials reported the effects of sodium-glucose cotransporter (SGLT) inhibitors in type 1 diabetes patients. This meta-analysis aimed to assess the efficacy and safety of SGLT inhibitors in type 1 diabetes patients. MATERIALS AND METHODS: Relevant studies were identified in the PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure and Wan Fang databases through 1 April 2020. Differences were expressed as the 95% confidence interval (CI) or weighted mean difference (WMD) for continuous outcomes, and risk ratio (RR) for discontinuous outcomes. RESULTS: A total of 13 RCTs with 7,962 cases were included. SGLT inhibitors reduced the fasting plasma glucose level (WMD -1.320 mmol/L, 95% CI -1.609 to -1.031, P < 0.001), glycated hemoglobin level (WMD -0.386%, 95% CI -0.431 to -0.342, P < 0.001) and daily total insulin dose (WMD -5.403, 95% CI -7.218 to -3.859, P < 0.001). However, higher risks of diabetic ketoacidosis (RR 5.042, 95% CI 3.160-8.046, P < 0.001), urinary tract infections (RR 1.259, 95% CI 1.034-1.533,P = 0.022) and genital infections (RR 2.995, 95% CI 1.953-4.594, P < 0.001) were associated with SGLT inhibitors, but SGLT inhibitors did not increase the hypoglycemia risk (RR 0.980, 95% CI 0.840-1.144,P = 0.799). In subgroup analysis, with a significant reduction of fasting plasma glucose, glycated hemoglobin and daily insulin doses, SGLT1/2 inhibitor did not increase genitourinary tract infections compared with a placebo. CONCLUSIONS: SGLT2 and SGLT1/2 inhibitors can improve glycemic control in patients with type 1 diabetes.