Although metabolic abnormalities commonly occur in non-obese Asians, their pathogenesis is not fully understood. Proton magnetic resonance spectroscopy has been used to analyze intracellular lipids in humans, and results suggest that ectopic fat accumulation in muscle and liver may induce insulin resistance in each tissue independently of obesity. Thus, measurement of ectopic fat currently plays an important role in the study of insulin resistance in non-obese Asians. In addition, studies using 2-step hyperinsulinemic euglycemic clamp with a glucose tracer may clarify how tissue-specific insulin resistance in muscle, liver, and adipose tissue contributes to the development of metabolic disease in non-obese Japanese. Although numerous studies have elucidated the pathophysiology of insulin resistance in obese subjects, research on “metabolic gradation,” defined as the gradual transition from an insulin-sensitive to an insulin-resistant state, is less common, especially in terms of early metabolic changes. This review addresses a simple question: when and how is insulin resistance induced in non-obese East Asians? Several studies revealed that impaired insulin clearance and hyperinsulinemia not only compensated for insulin resistance, but also secondarily facilitated insulin resistance and weight gain. In this regard, we recently found that impaired insulin clearance and hyperinsulinemia could occur in apparently healthy subjects without significant insulin resistance, suggesting that this change may be an initial trigger that drives subsequent insulin resistance and weight gain. Further research is required to clarify the pathogenesis of metabolic gradation in non-obese Asians.
The aim of this study was to investigate whether daily glycemic profiles and treatment satisfaction would be changed after switching from once-daily 25-mg alogliptin plus twice-daily 250-mg metformin to the fixed-dose combination of 25-mg alogliptin and 500-mg metformin once daily in type 2 diabetic patients. Twenty adult Japanese type 2 diabetic patients in whom once-daily 25-mg alogliptin plus twice-daily 250-mg metformin were switched to the fixed-dose combination of 25-mg alogliptin and 500-mg metformin once daily participated. Before and one month after the switch, participants were asked to perform one day of seven-point self-monitoring of blood glucose (SMBG), to wear a sensor of flash glucose monitoring for up to 14 days, and to respond to a questionnaire for treatment satisfaction. As a result, the SMBG profiles were significantly changed after the switch (p = 0.021); blood glucose levels 2 hours after breakfast were significantly elevated (p = 0.022), whereas those 2 hours after lunch were significantly reduced (p = 0.036). The flash glucose monitoring also demonstrated a significant change of daily glucose profiles (p < 0.001). The risk of glucose levels <80 mg/dL were decreased from evening to morning, while the risk of glucose levels ≥140 mg/dL were increased. Mean 24-hour glucose values were increased by 5 mg/dL on average (p < 0.001). Treatment satisfaction was significantly improved after the switch (p < 0.001). In conclusion, daily glycemic profiles were significantly changed after switching from once-daily 25-mg alogliptin plus twice-daily 250-mg metformin to the once-daily fixed-dose combination in Japanese type 2 diabetic patients. Treatment satisfaction was significantly improved after the switch.
Monocarboxylate transporter 8 (MCT8) facilitates T3 uptake into cells. Mutations in MCT8 lead to Allan-Herndon-Dudley syndrome (AHDS), which is characterized by severe psychomotor retardation and abnormal thyroid hormone profile. Nine uncharacterized MCT8 mutations in Japanese patients with severe neurocognitive impairment and elevated serum T3 levels were studied regarding the transport of T3. Human MCT8 (hMCT8) function was studied in wild-type (WT) or mutant hMCT8-transfected human placental choriocarcinoma cells (JEG3) by visualizing the locations of the proteins in the cells, detecting specific proteins, and measuring T3 uptake. We identified 6 missense (p.Arg445Ser, p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, and p.Gly312Arg), 2 frameshift (p.Arg355Profs*64 and p.Tyr550Serfs*17), and 1 deletion (p.Pro561del) mutation(s) in the hMCT8 gene. All patients exhibited clinical characteristics of AHDS with high free T3, low-normal free T4, and normal-elevated TSH levels. All tested mutants were expressed at the protein level, except p.Arg355Profs*64 and p.Tyr550Serfs*17, which were truncated, and were inactive in T3 uptake, excluding p.Arg445Ser and p.Pro561del mutants, compared with WT-hMCT8. Immunocytochemistry revealed plasma membrane localization of p.Arg445Ser and p.Pro561del mutants similar with WT-hMCT8. The other mutants failed to localize in significant amount(s) in the plasma membrane and instead localized in the cytoplasm. These data indicate that p.Arg445Ser and p.Pro561del mutants preserve residual function, whereas p.Asp498Asn, p.Gly276Arg, p.Gly196Glu, p.Gly401Arg, p.Gly312Arg, p.Arg355Profs*64, and p.Tyr550Serfs*17 mutants lack function. These findings suggest that the mutations in MCT8 cause loss of function by reducing protein expression, impairing trafficking of protein to plasma membrane, and disrupting substrate channel.
This subgroup analysis of STELLA-LONG TERM, an ongoing 3-year post-marketing surveillance study on the long-term efficacy and safety of ipragliflozin, assessed the effect of ipragliflozin on liver function in type 2 diabetes mellitus (T2DM) patients. Patients were divided according to baseline liver function (normal [male: ALT ≤30, female: ALT ≤20], abnormal [male: ALT ≥31, female: ALT ≥21]). We evaluated changes in aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (γ-GTP), alkaline phosphatase (ALP), and fatty liver index (FLI) at 3 months of treatment; the proportion of patients with abnormal liver function whose liver function normalized after 3 months of treatment; and correlations between changes in ALT levels and efficacy variables/laboratory values. Liver function was normal in 2,570 and abnormal in 3,239 patients. Only patients with abnormal liver function showed a statistically/clinically significant decrease in AST, ALT, γ-GTP, and ALP levels at 3 months (all p < 0.05 vs. baseline). The FLI significantly decreased from 63.2677 ± 26.4363 (baseline) to 56.7137 ± 27.6484 (3 months) (p < 0.05) in the overall patient population. Liver function normalized in 20.5% (543/2,648) of patients with abnormal liver function. There was no obvious correlation between changes in ALT and changes in efficacy/laboratory parameters. Liver function improved after 3-month treatment with ipragliflozin in T2DM patients with abnormal liver function.
It is known that long-chain fatty acids bind to free fatty acid receptor 1 (Ffar1), also known as G protein-coupled receptor 40 (GPR40), and amplify glucose-stimulated insulin secretion (GSIS) from pancreatic β-cells and that Ffar1 agonists facilitates insulin secretion and ameliorates glycemic control. On the other hands, pancreatic and duodenal homeobox factor 1 (Pdx1) is an important transcription factor for various β-cell-related genes including insulin gene and thereby contributes to the maintenance of mature β-cell function. The aim of this study was to evaluate how Ffar1 expression in β-cells is altered under diabetic conditions. In this study, we used male obese type 2 diabetic mice and control mice. We evaluated Ffar1 and Pdx1 mRNA and protein expression levels in both mice. In addition, we examined whether Pdx1 is a possible regulator of Ffar1 expression using small interfering RNA for Pdx1 (siPdx1) in β-cell-derived cell line. As the results, Ffar1 mRNA and protein expression in β-cells were significantly lower in obese type 2 diabetic db/db mice compared to control mice which was accompanied by the decreased expression of Pdx1. In addition, down-regulation of Pdx1 expression using siPdx1 suppressed Ffar1 expression. Furthermore, adenoviral Pdx1 overexpression significantly increased Ffar1 expression. In conclusion, Ffar1 expression is markedly down-regulated under diabetic conditions which is accompanied by decreased expression of Pdx1. Furthermore, it is likely that Pdx1 is a regulator of Ffar1 expression in β-cells.
We conducted a systematic review and meta-analysis to evaluate the effect of Berberine on glucose in patients with type 2 diabetes mellitus and identify potential factors may modifying the hypoglycemic effect. We searched PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database to identify randomized controlled trials that investigated the effect of Berberine. We calculated weighted mean differences (WMD) and 95% confidence interval (CI) for fasting plasma glucose (FPG), postprandial plasma glucose (PPG) and glycated haemoglobin (HbA1c) levels. Twenty-eight studies were identified for analysis, with a total of 2,313 type 2 diabetes mellitus (T2DM) patients. The pool data showed that Berberine treatment was associated with a better reduction on FPG (WMD = –0.54 mmol/L, 95% CI: –0.77 to –0.30), PPG (WMD = –0.94 mmol/L, 95% CI: –1.27 to –0.61), and HbA1c (WMD = –0.54 mmol/L, 95% CI: –0.93 to –0.15) than control groups. Subgroup-analyses indicated that effects of Berberine on blood glucose became unremarkable as the treatment lasted more than 90 days, the daily dosage more than 2 g/d and patients aged more than 60 years. The efficiency of Berberine combined with hypoglycaemics is better than either Berberine or hypoglycaemic alone. The dosage and treatment duration of Berberine and patients’ age may modify the effect.
The human homologue of flightless-I (FLII) belong to the gelsolin protein family and contain a gelsolin-like domain at the C-terminus and a leucine-rich repeat (LRR) domain at the N-terminus. FLII regulates estrogen receptor alpha (ERα) and glucocorticoid receptor (GR)-mediated transcription by direct interaction through different domains, suggestive of its potential role in the crosstalk between the ERα and GR signaling pathway. Here, we demonstrate that FLII plays a critical role in GR-mediated repression of ERα target gene expression. In FLII-depleted cells, the reduction in 17-β-estradiol (E2)-induced ERα occupancy following treatment with dexamethasone (Dex) at the estrogen responsive element (ERE) site of the ERα target gene was significantly inhibited. The ERE binding of GR by the cotreatment with E2 and Dex was significantly inhibited by FLII depletion, indicating that FLII is required for the recruitment of GR at the ERE sites of ERα target genes. In addition, the recruitment of ERα-induced FLII to ERE sites was significantly reduced by Dex treatment. In protein binding assays, GR inhibited the E2-induced interaction between ERα and FLII, suggesting that GR interferes with the binding of ERα and FLII at the ERα target genes, resulting in the release of ERα and FLII from EREs. Taken together, our data reveal an unknown mechanism by which the transcription coactivator FLII regulates the GR-mediated repression of ERα target gene expression in MCF-7 cells.
This study assessed the association of muscle mass with insulin resistance, evaluated from the insulin sensitivity index (ISI), in Japanese patients with gestational diabetes mellitus (GDM). Consecutive patients with GDM (n = 96) admitted to St. Marianna University Hospital between October 2015 and March 2018 for initial education and glycemic control were enrolled in a prospective observational study. Insulin resistance was evaluated by measuring the ISI and body composition was assessed by bioelectrical impedance analysis. The subjects were aged 34.4 ± 4.8 years (mean ± SD) and their body mass index (BMI) before pregnancy was 22.3 ± 4.0 kg/m2. Fifty-three patients (55.2%) had a history of diabetes in first-degree relatives. The ISI was 7.2 ± 3.3, appendicular skeletal muscle mass (ASM) was 17.0 ± 2.1 kg, and fat mass (FM) was 18.8 ± 8.2 kg. The ASM/FM ratio was 1.02 ± 0.34. There was a positive correlation between FM and ASM (r = 0.734, p < 0.001). To adjust for confounders when evaluating the association of ASM with ISI, multivariate analysis was conducted using age, family history of diabetes, and BMI as variables. In this analysis, the ASM/FM ratio showed a significant positive correlation with ISI (β = 0.303, p = 0.020). These findings suggest that inadequate ASM/FM ratio is important for the development of insulin resistance in Japanese patients with GDM. Excessive emphasis on dieting rather than health might increase the risk of GDM by reducing the muscle mass below the level that maintains normal glucose metabolism.
Premature ovarian insufficiency (POI) is a common endocrine disorder featured by the triad constituting of amenorrhea for at least four months, to date, the molecular pathogenesis of POI is largely undetermined. Despite several investigations have reported an increase in reactive oxygen species (ROS) content in idiopathic POI, the role of mitochondrial DNA (mtDNA) mutations/variants in the progression of POI has not been widely investigated. The current study aimed to explore the association between mt-tRNA mutations/variants and POI; we first used the PCR-Sanger sequencing to detect the mutations/variants in mt-tRNA genes from 50 POI patients and 30 healthy subjects. In addition, we evaluated the mitochondrial functions by using trans-mitochondrial cybrid cells containing these potential pathogenic mt-tRNA mutations. Consequently, five mutations: tRNALeu(UUR) C3303T, tRNAMet A4435G, tRNAGln T4363C, tRNACys G5821A and tRNAThr A15951G were identified. Notably, these mutations occurred at the extremely conserved nucleotides of the corresponding mt-tRNAs and may result the failure in mt-tRNA metabolism and subsequently lead to the impairment in mitochondrial protein synthesis. Furthermore, biochemical and molecular analyses of the cybrid cells containing these mutations showed a significantly lower level of ATP production when compared with the controls, whereas the ROS levels were much higher in POI patients carrying these mt-tRNA mutations, strongly indicated that these mt-tRNA mutations may cause the mitochondrial dysfunction, and play active roles in the progression and pathogensis of POI. Together, this study shaded additional light on the molecular mechanism of POI that was manifestated by mt-tRNA mutations.
Angiopoietin-like protein 8 (ANGPTL8) is a newly discovered adipokine plays an important role in energy homoeostasis, obesity and type 2 diabetes (T2D). Although lifestyle modification in obesity and T2D is known to offer metabolic benefits, there is paucity of comprehensive data on change in ANGPTL8. We investigated the effect of lifestyle intervention on ANGPTL8 concentrations. 384 obese/overweight adults with newly diagnosed T2D were randomly assigned (1:1:1) to diet (n = 128), diet + activity (n = 128) or usual care (control, n = 128) groups. All patients received usual care. Besides, the diet group received a calorie-restricted diet aiming for a weight loss of 5–10%. The diet + activity group additionally received a pedometer-based walking program. Primary outcome was change in ANGPTL8 concentration at 6 months. Data were analyzed according to intention-to-treat. From baseline to 6 months, the median ANGPTL8 level changed from 804.38 pg/mL to 792.86 pg/mL in control group. Compared with control, ANGPTL8 decreased with diet (baseline-adjusted between-group difference was –121.00 pg/mL, 95% CI –177.47 to –64.53; p < 0.0001) and diet + activity (–126.16 pg/mL, –181.21 to –71.11; p < 0.0001). There was no greater effect of diet + activity compared with diet (–5.16 pg/mL, –53.63 to 43.31; p = 0.8348). Both effects disappeared after adjusting for change in body fat, but did not differ significantly when adjusting for physical activity. A 6-month intervention inducing weight loss by a calorie-restricted diet or diet + activity, resulted in significant decrease on ANGPTL8 concentration. These effects were established by change in total body fat, and not by change in physical activity.
Soft-drink diabetic ketosis, characterized by acute onset ketosis induced by excessive ingestion of sugar-containing drinks, is often seen in obese, young patients, even with undiagnosed type 2 diabetes. We herein report a 15-year-old obese patient with the apolipoprotein E4/2 phenotype, in whom eruptive xanthomas lead to a diagnosis of soft-drink diabetic ketosis. He developed multiple asymptomatic yellowish papules on the auricles, back, buttocks and the extensor surfaces of the elbows and knees. He initially visited a dermatology clinic and his blood triglyceride and HbA1c levels were found to be 6,490 mg/dL and 16.5%, respectively. He was referred to our hospital for treatment of hyperglycemia and hypertyriglyceridemia. On admission, he had ketonuria and increased blood levels of 3-hydroxybutylate and acetoacetate. He habitually drank 1–3 litters of sweet beverages daily to quench his thirst. Therefore, “soft-drink diabetic ketosis” was diagnosed. Severe hypertriglyceridemia was considered to have been a consequence of impaired insulin action and his apolipoprotein E4/2 phenotype. We treated the diabetic ketosis and hypertriglyceridemia with intensive insulin therapy and a fat-restricted diet. At discharge, he no longer required insulin therapy and his blood glucose levels were controlled with metformin and voglibose. Along with amelioration of the hyperglycemia, triglyceride levels decreased to 247 mg/dL without administration of anti-hyperlipidemia agents. The eruptive xanthoma lesions gradually diminished in size and number and eventually disappeared by 12 months. This case provides an instructive example of eruptive xanthomas serving as a sign of severe dysregulation, not only of lipid, but also glucose, metabolism.