Decreased AdipoR1 signaling and its implications for obesity-induced male infertility

Obesity is among the risk factors for male infertility. Although several mechanisms underlying obesity-induced male subfertility have been reported, the entire mechanism of obesity-induced male infertility still remains unclear. Here, we show that sperm count, sperm motility and sperm fertilizing ability were decreased in male mice fed a high-fat diet and that the expression of the AdipoR1 gene and protein was decreased, and the expression of pro-apoptotic genes and protein increased, in the testis from mice fed a high-fat diet. Moreover, we demonstrate that testes weight, sperm count, sperm motility and sperm fertilizing ability were significantly decreased in AdipoR1 knockout mice compared to those in wild-type mice; furthermore, the phosphorylation of AMPK was decreased, and the expression of pro-apoptotic genes and proteins, caspase-6 activity and pathologically apoptotic seminiferous tubules were increased, in the testis from AdipoR1 knockout mice. Furthermore, study findings show that orally administrated AdipoRon decreased caspase-6 activity and apoptotic seminiferous tubules in the testis, thus ameliorating sperm motility in male mice fed a high-fat diet. This was the first study to demonstrate that decreased AdipoR1/AMPK signaling led to increased caspase-6 activity/increased apoptosis in the testis thus likely accounting for male infertility.

Association Between Vonoprazan and the Risk of Gastric Cancer After Helicobacter pylori Eradication

BACKGROUND & AIMS

Potassium-competitive acid blockers (PCABs) have been increasingly used to treat upper gastrointestinal disorders, replacing proton pump inhibitors (PPIs). Whereas PPIs are associated with an increased risk of gastric cancer (GC) after Helicobacter pylori (Hp) eradication, it is uncertain whether PCABs carry the same risk.

METHODS

Using a population-based claims database in Japan, we identified patients who were prescribed a clarithromycin-based first regimen of Hp eradication between 2015 and 2018. Patients who failed this regimen and those diagnosed with GC before or within 1 year after Hp eradication were excluded. We compared GC incidence between PCAB users and histamine type-2 receptor antagonist (H2RA) users, matching them on the basis of propensity scores calculated with considerations for age, sex, smoking, alcohol consumption, comorbidities, and co-administered medications. PCABs included only vonoprazan in this study.

RESULTS

Among 54,055 patients, 568 (1.05%) developed GC during the follow-up period (mean, 3.65 years). The cumulative incidence of GC was 1.64% at 3 years, 2.02% at 4 years, and 2.36% at 5 years in PCAB users and 0.71% at 3 years, 1.04% at 4 years, and 1.22% at 5 years in H2RA users. The use of PCABs was associated with a higher GC risk (matched hazard ratio, 1.92; 95% confidence interval, 1.13-3.25; P = .016). Longer PCAB use and high-dose PCAB use were significantly associated with higher incidence of GC. Sensitivity analyses showed the risk of GC incidence among PCAB users was comparable with that of PPI users.

CONCLUSIONS

The use of PCABs was associated with an increased risk of GC among Hp-eradicated patients, with duration/dose response effects.

Increased expression of TNFRSF14 and LIGHT in biliary epithelial cells of patients with primary sclerosing cholangitis

BACKGROUND AND AIMS

There is a lack of biliary epithelial molecular markers for primary sclerosing cholangitis (PSC). We analyzed candidates from disease susceptibility genes identified in recent genome-wide association studies (GWAS).

METHODS

Expression levels of GWAS genes were analyzed in archival liver tissues of patients with PSC and controls. Immunohistochemical analysis was performed to evaluate expression levels in the biliary epithelia of PSC (N = 45) and controls (N = 12). Samples from patients with primary biliary cholangitis (PBC) were used as disease controls (N = 20).

RESULTS

Hepatic expression levels of ATXN2, HHEX, PRDX5, MST1, and TNFRSF14 were significantly altered in the PSC group. We focused on the immune-related receptor, TNFRSF14. Immunohistochemistry revealed that high expression of TNFRSF14 in biliary epithelial cells was observed only in the PSC group. In addition, the expression of LIGHT, which encodes a TNFRSF14-activating ligand, was increased in PSC liver. Immunohistochemistry showed that high expression of LIGHT was more common in PSC biliary epithelia (53%) than in the PBC (15%) or control (0%) groups; moreover, it was positively associated with fibrotic progression, although it was not an independent prognostic factor.

CONCLUSIONS

TNFRSF14 and LIGHT are promising candidate markers for PSC.

Hepatic FASN deficiency differentially affects nonalcoholic fatty liver disease and diabetes in mouse obesity models

Nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes are interacting comorbidities of obesity, and increased hepatic de novo lipogenesis (DNL), driven by hyperinsulinemia and carbohydrate overload, contributes to their pathogenesis. Fatty acid synthase (FASN), a key enzyme of hepatic DNL, is upregulated in association with insulin resistance. However, the therapeutic potential of targeting FASN in hepatocytes for obesity-associated metabolic diseases is unknown. Here, we show that hepatic FASN deficiency differentially affects NAFLD and diabetes depending on the etiology of obesity. Hepatocyte-specific ablation of FASN ameliorated NAFLD and diabetes in melanocortin 4 receptor-deficient mice but not in mice with diet-induced obesity. In leptin-deficient mice, FASN ablation alleviated hepatic steatosis and improved glucose tolerance but exacerbated fed hyperglycemia and liver dysfunction. The beneficial effects of hepatic FASN deficiency on NAFLD and glucose metabolism were associated with suppression of DNL and attenuation of gluconeogenesis and fatty acid oxidation, respectively. The exacerbation of fed hyperglycemia by FASN ablation in leptin-deficient mice appeared attributable to impairment of hepatic glucose uptake triggered by glycogen accumulation and citrate-mediated inhibition of glycolysis. Further investigation of the therapeutic potential of hepatic FASN inhibition for NAFLD and diabetes in humans should thus consider the etiology of obesity.

Association of glucagon-like peptide-1 receptor agonist treatment with gastric residue in an esophagogastroduodenoscopy

AIMS/INTRODUCTION

Previous studies have reported that the glucagon-like peptide-1 receptor agonist (GLP-1RA) delays gastric emptying, and gastric emptying was assessed by the ¹³ C breath test or paracetamol absorption technique. However, neither of them is clinically familiar in real-world clinical practice. The purpose of the present study was to investigate the association between GLP-1RA treatment and gastric residue in an esophagogastroduodenoscopy.

MATERIALS AND METHODS

This study was a matched pair case-control study. The study population consisted of 1,128 individuals with diabetes who had esophagogastroduodenoscopy at our clinic between July 2020 and June 2022. To account for differences in characteristics, such as age, sex, insulin treatment and glycated hemoglobin, we carried out a one-to-one nearest neighbor propensity score matching analysis between diabetes patients with and without GLP-1RA treatment. After matching, we compared the presence of gastric residue in an esophagogastroduodenoscopy by the McNemar test between patients with and without GLP-1RA treatment.

RESULTS

After the propensity score matching, we selected 205 pairs. In the propensity score-matched comparison, the proportion of gastric residue was statistically significantly higher in the GLP-1RA treatment group (0.49% vs 5.4%, P = 0.004). The details of GLP-1RA prescribed for the 11 patients with gastric residue were liraglutide once daily 1.8 mg (n = 2), dulaglutide once weekly 0.75 mg (n = 5), semaglutide once weekly 0.5 mg (n = 2) and semaglutide once weekly 1.0 mg (n = 2).

CONCLUSION

GLP-1RA treatment is associated with gastric residue in an esophagogastroduodenoscopy in patients with diabetes.

Association of self-stigma with glycated hemoglobin: A single-center, cross-sectional study of adults with type 1 diabetes in Japan

AIMS/INTRODUCTION

There has been an increase in research on diabetes-related stigma and its association with glycated hemoglobin (HbA1c) over the past years. However, little is known about the association of self-stigma with HbA1c in persons with type 1 diabetes. This study aims to examine the association between self-stigma and HbA1c in Japanese people with type 1 diabetes.

MATERIALS AND METHODS

This cross-sectional study was conducted at a clinic in Tokyo. Questionnaires using nine items from the Japanese version of the Self-Stigma Scale was distributed to outpatients with type 1 diabetes, aged ≥18 years. We excluded outpatients with serious mental disorder, those who required urgent medical treatment or received hemodialysis. Adjusted linear regression analyses tested the association between the score of the 9-item Self-Stigma Scale and HbA1c.

RESULTS

Questionnaires were distributed to 166 eligible participants. A total of 109 participants were included in the final analysis after excluding participants with incomplete answers and laboratory data. After adjusting for age, sex, employment status, body mass index, duration of diabetes and insulin secretion, there was a significant positive association between self-stigma and HbA1c (β = 0.05, 95% confidence interval 0.01 to 0.08).

CONCLUSIONS

This cross-sectional study showed a significant association between self-stigma and HbA1c in persons with type 1 diabetes. Addressing self-stigma might be as equally essential as measuring HbA1c in evaluating glycemic outcome among individuals with type 1 diabetes.

The transcription factor ATF3 switches cell death from apoptosis to necroptosis in hepatic steatosis in male mice

Hepatocellular death increases with hepatic steatosis aggravation, although its regulation remains unclear. Here we show that hepatic steatosis aggravation shifts the hepatocellular death mode from apoptosis to necroptosis, causing increased hepatocellular death. Our results reveal that the transcription factor ATF3 acts as a master regulator in this shift by inducing expression of RIPK3, a regulator of necroptosis. In severe hepatic steatosis, after partial hepatectomy, hepatic ATF3-deficient or -overexpressing mice display decreased or increased RIPK3 expression and necroptosis, respectively. In cultured hepatocytes, ATF3 changes TNFα-dependent cell death mode from apoptosis to necroptosis, as revealed by live-cell imaging. In non-alcoholic steatohepatitis (NASH) mice, hepatic ATF3 deficiency suppresses RIPK3 expression and hepatocellular death. In human NASH, hepatocellular damage is correlated with the frequency of hepatocytes expressing ATF3 or RIPK3, which overlap frequently. ATF3-dependent RIPK3 induction, causing a modal shift of hepatocellular death, can be a therapeutic target for steatosis-induced liver damage, including NASH.

Clinical features and sulfonylurea usage among outpatients with diabetes aged ≥90 years in an urban diabetes clinic in Tokyo

AIMS/INTRODUCTION

Aging of society is accelerating in many countries. The purpose of this study was to describe the clinical features and sulfonylurea usage among diabetes outpatients aged ≥90 years (nonagenarians).

MATERIALS AND METHODS

This study was a retrospective observational study. The study population consisted of 69 nonagenarian diabetes outpatients and 857 diabetes outpatients aged <90 years. Patients were classified into four groups: group 1, <65 years; group 2, 65-74 years; group 3, 75-89 years; and group 4, ≥90 years. The presence of hypoglycemic episodes was defined as having self-reported symptoms, or self-monitored or clinically measured blood glucose level <70 mg/dL.

RESULTS

The median glycated hemoglobin (HbA1c) in group 1 and group 4 was 7.0% and 7.2%, respectively (P = 0.506). The proportion of sulfonylurea treatment in group 4 was 45.5%, which is significantly higher compared with the other three groups (20.0-27.8%, P < 0.001). In group 4, there was no difference between patients with or without sulfonylurea in age, sex, body mass index, HbA1c and number of antihyperglycemic agents. Five out of 25 nonagenarian sulfonylurea-treated patients had hypoglycemic episodes within the last 2 years, their HbA1c were all 7.0 ≤ HbA1c < 8.0, and sulfonylurea or insulin was tapered in all cases after confirming hypoglycemia. Tapering dosage was attempted in all 25 sulfonylurea-treated nonagenarian patients, but 15 needed to continue sulfonylurea for glycemic control, and 10 continued sulfonylurea with unknown reasons from their medical records.

CONCLUSIONS

Although tapering the dosage of sulfonylurea was attempted in nonagenarian patients, sulfonylurea was widely continued for glycemic control. Reverse clinical inertia may exist in some sulfonylurea-treated nonagenarian patients.

Substitution of telemedicine for clinic visit during the COVID-19 pandemic of 2020-comparison of telemedicine and clinic visit

Aims/Introduction

The purpose of this retrospective observational cohort study was to compare outpatient diabetes care and glycated hemoglobin (HbA1c) level during the coronavirus disease 2019 pandemic in 2020 with 2019, and to compare the glucose‐lowering effect of telemedicine and clinic visits during the state of emergency in Japan declared from 7 April to 25 May (inter‐period) 2020.

Materials and Methods

A total of 13 weeks before and after the inter‐period were designated as the pre‐period and post‐period, respectively. The number of study participants who had clinic visits during the pre‐period and the post‐period were 3,333 in 2020 and 3,608 in 2019. Propensity score matching was carried out to compare the effect of telemedicine and clinic visits on diabetes control in 2020 among diabetes patients with insufficient glucose control (HbA1c ≥7%). The primary outcome was post‐period HbA1c.

Results

The major difference between 2020 and 2019 was the use of telemedicine in 2020. After adjustment for age, sex, diabetes type, pre‐period HbA1c and pre‐period body mass index, glycemic control evaluated by HbA1c was significantly worse in the post‐period of 2020 than 2019. In the propensity score‐matched 618 pairs, the clinic visit group had significantly better post‐period HbA1c than the telemedicine group (7.5% vs 7.4%, P = 0.023).

Conclusions

Glycemic control was slightly, but significantly, worse in 2020 than 2019. Although telemedicine significantly improved glycemic control during the coronavirus disease 2019 pandemic in 2020, clinic visits improved HbA1c significantly more. The substitution of telemedicine for clinic visits appears to be a viable option under emergency conditions, but clinic visits might be a better option when possible.

Synergistic association of the copper/zinc ratio under inflammatory conditions with diabetic kidney disease in patients with type 2 diabetes: The Asahi Diabetes Complications Study

Aims/Introduction

We aimed to study the relationships among the copper (Cu)/zinc (Zn) ratio, inflammatory biomarkers, and the prevalence of diabetic kidney disease (DKD) in patients with type 2 diabetes.

Materials and Methods

A cross‐sectional study was performed on 651 patients with type 2 diabetes. DKD was defined as a urinary albumin‐to‐creatinine ratio of ≥30 mg/g creatinine and/or an estimated glomerular filtration rate using cystatin C of < 60 mL/min/1.73 m². Areas under the curves (AUCs), cutoff values, and thresholds for detecting DKD were determined for the Cu/Zn ratio, soluble tumor necrosis factor‐α receptor 1 (sTNFαR1), and high‐sensitivity C‐reactive protein (hsCRP). Patients were categorized by each cutoff value of sTNFαR1 and the Cu/Zn ratio. Odds ratios (ORs) and biological interactions for the prevalence of DKD were determined.

Results

DKD was identified in 220 patients. AUC/optimal cutoff values were 0.777/1300 pg/mL for sTNFαR1, 0.603/1.1648 for the Cu/Zn ratio, and 0.582/305 ng/mL for hsCRP. The ORs for DKD were higher, but not significantly, in the sTNFαR1 < 1300 and Cu/Zn ≥ 1.1648 group, significantly higher in the sTNFαR1 ≥ 1300 and Cu/Zn < 1.1648 group (P < 0.0001), and further synergistically elevated in the sTNFαR1 ≥ 1300 and Cu/Zn ≥ 1.1648 group (P < 0.0001) compared with the sTNFαR1 < 1300 and Cu/Zn < 1.1648 group after multivariable adjustment. Levels of sTNFαR1 were significantly higher in the sTNFαR1 ≥ 1300 and Cu/Zn ≥ 1.1648 group than in the sTNFαR1 ≥ 1300 and Cu/Zn < 1.1648 group (P = 0.0006).

Conclusions

Under an inflammatory initiation signal of elevated serum sTNFαR1 levels, an increase in the Cu/Zn ratio may further exacerbate inflammation and is synergistically associated with a high prevalence of DKD in patients with type 2 diabetes.

Association of insulin treatment with gastric residue during an esophagogastroduodenoscopy

The purpose of this study was to investigate the association of glycemic control and diabetes treatment to gastric residue observed during an esophagogastroduodenoscopy. Among 6,592 individuals who had esophagogastroduodenoscopy at our clinic between 2003 and 2019, we retrospectively and longitudinally identified those who had gastric residue during an esophagogastroduodenoscopy. Other data collected were age, sex, diagnosis of diabetes, glycated hemoglobin and diabetes medication. Cox proportional hazards models were used to assess the association of these data with the occurrence of gastric residue. To the best of our knowledge, this is the first retrospective cohort study finding that undergoing insulin treatment is a risk factor for gastric residue independent of age, sex and diabetes or glycated hemoglobin.

Thresholds for postprandial hyperglycemia and hypertriglyceridemia associated with increased mortality risk in type 2 diabetes patients: A real-world longitudinal study

AIMS/INTRODUCTION

To identify thresholds for postprandial hyperglycemia and hypertriglyceridemia predictive of all-cause mortality in patients with type 2 diabetes.

MATERIALS AND METHODS

A total of 1,928 patients with type 2 diabetes visited our clinic for the first time from 1995 to 1999 and were followed up for ≥1 year. During the first year, 2-h post-breakfast blood glucose (2h-BG) levels were measured in 1,122 patients (BG cohort) and postprandial serum triglyceride (ppTG) levels were measured in 1,826 patients (TG cohort). Patients were retrospectively followed until 2017 and administered questionnaires. Associations between 2h-BG and ppTG levels and mortality risk were assessed by the multivariate Cox regression analysis.

RESULTS

Over of 17,429 person-years, 162 deaths occurred in the BG cohort, and over 28,026 person-years, 253 deaths occurred in the TG cohort. Hazard ratios (HRs) with 95% confidence intervals for all-cause mortality per 1-standard deviation increases in 2h-BG and ppTG were 1.34 (1.08-1.67) and 1.24 (1.06-1.45), respectively. HRs showed increasing trends across quintiles of 2h-BG (P = 0.034) and ppTG (P = 0.007). The HR was significantly elevated (2.37, 1.26-4.47) in the fifth quintile of 2h-BG (≥13.8 mmol/L) compared with the first quintile (<7.0 mmol/L; P = 0.008). The HR was also significantly elevated (1.63, 1.03-2.60) in the fifth quintile of ppTG (≥2.30 mmol/L) compared with the first quintile (<0.91 mmol/L; P = 0.038).

CONCLUSIONS

Postprandial hyperglycemia and hypertriglyceridemia were associated with all-cause mortality in patients with type 2 diabetes. We propose thresholds of 13.8 mmol/L 2h-BG and 2.30 mmol/L ppTG to identify patients at increased risk of mortality.

Diabetes management by either telemedicine or clinic visit improved glycemic control during the coronavirus disease 2019 pandemic state of emergency in Japan

The purpose of this retrospective cohort study at a Tokyo diabetes clinic was to evaluate the effect of telemedicine and clinic visit on glycated hemoglobin (HbA1c) during the coronavirus disease 2019 state of emergency. The effect of telemedicine and clinic visit during the emergency period on the post‐emergency measured HbA1c was evaluated by multiple regression models and logistic regression models adjusted for age, sex, type of diabetes, pre‐emergency HbA1c and body mass index, and body mass index change during the emergency period. Among 2,727 patients who visited the clinic before and after the emergency period, the interval between clinic visits during the emergency period was significantly associated with HbA1c improvement. Telemedicine and clinic visit were independently associated with HbA1c improvement when pre‐emergency HbA1c was ≥7%. In conclusion, clinic visit and telemedicine during the coronavirus disease 2019 emergency period were both independently effective in HbA1c improvement in Japanese diabetes patients who had insufficient HbA1c control.

Hepatocellular carcinoma development in diabetic patients: a nationwide survey in Japan

BACKGROUND

Although type 2 diabetes mellitus (T2DM) is a known risk factor for hepatocellular carcinoma (HCC) development, the annual incidence in diabetes patients is far below the threshold of efficient surveillance. This study aimed to elucidate the risk factors for HCC in diabetic patients and to determine the best criteria to identify surveillance candidates.

METHODS

The study included 239 patients with T2DM who were diagnosed with non-viral HCC between 2010 and 2015, with ≥ 5 years of follow-up at diabetes clinics of 81 teaching hospitals in Japan before HCC diagnosis, and 3277 non-HCC T2DM patients from a prospective cohort study, as controls. Clinical data at the time of and 5 years before HCC diagnosis were collected.

RESULTS

The mean patient age at HCC diagnosis was approximately 73 years, and 80% of the patients were male. The proportion of patients with insulin use increased, whereas the body mass index (BMI), proportion of patients with fatty liver, fasting glucose levels, and hemoglobin A1c (HbA1c) levels decreased significantly in 5 years. In the cohort study, 18 patients developed HCC during the mean follow-up period of 4.7 years with an annual incidence of 0.11%. Multivariate logistic regression analyses showed that the FIB-4 index was an outstanding predictor of HCC development along with male sex, presence of hypertension, lower HbA1c and albumin levels, and higher BMI and gamma-glutamyl transpeptidase levels. Receiver-operating characteristic analyses showed that a FIB-4 cut-off value of 3.61 could help identify high-risk patients, with a corresponding annual HCC incidence rate of 1.1%.

CONCLUSION

A simple calculation of the FIB-4 index in diabetes clinics can be the first step toward surveillance of HCC with a non-viral etiology.

5-Aminolevulinic acid-mediated photodynamic activity in patient-derived cholangiocarcinoma organoids

BACKGROUND

Accurate diagnosis of the disease extension of cholangiocarcinoma (CCA) is often difficult in clinical practice. The diagnostic yield of conventional pre-operative imaging or endoscopic procedures is sometimes insufficient for the evaluation of longitudinal spreading of CCA. Here we investigated the usefulness of 5-aminolevulinic acid (5-ALA) for the pre- or intra-operative diagnosis of CCA, using patient-derived organoids.

METHODS

Four CCA- and two adjacent tissue-derived organoids were established. After 5-ALA treatment, we assessed their photodynamic activity using fluorescence microscopy.

RESULTS

CCA organoids established from different patients showed diverse morphology in contrast to monolayer structures of non-tumor organoids, and had the ability to form subcutaneous tumors in immunodeficient mice. CCA organoids demonstrated remarkably high photodynamic activity based on higher accumulation of protoporphyrin IX as a metabolite of 5-ALA compared to non-tumor organoids (40-71% vs. < 4%, respectively). Importantly, cancer cell-specific high photodynamic activity distinguished the organoids originated from biliary stenotic lesions from those of non-stenotic lesions in a CCA patient. The high photodynamic activity did not depend on the expression profile of heme biosynthesis genes.

CONCLUSIONS

Distinct 5-ALA-based photodynamic activity could have diagnostic potential for the discrimination of CCA from non-tumor tissues.

Combined effect of diabetic retinopathy and diabetic kidney disease on all-cause, cancer, vascular and non-cancer non-vascular mortality in patients with type 2 diabetes: A real-world longitudinal study

AIMS/INTRODUCTION

We assessed the relationship between diabetic retinopathy (DR) and/or diabetic kidney disease (DKD) according to their severity and all-cause, cancer, vascular and non-cancer non-vascular mortality in real-world patients with type 2 diabetes.

MATERIALS AND METHODS

A total of 1,902 patients with type 2 diabetes were enrolled from 1995 to 1999 and followed to 2017. At baseline, DR was diagnosed in 374 patients, DKD in 529, vision-threatening DR in 123 and advanced DKD in 287. Patients were classified by the status of DR and DKD. Multivariate Cox regression analysis was carried out.

RESULTS

There were 266 deaths during a median follow-up period of 18.6 years. Among these, 92 were from cancer, 78 were from vascular causes and 82 were from non-cancer non-vascular causes. DR and/or DKD predicted all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality. Similarly, vision-threatening DR and/or advanced DKD predicted all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality. Hazard ratios for all-cause, vascular and non-cancer non-vascular mortality were highest in the DR(+)DKD(+) group, and higher in the DR(-)DKD(+) and the DR(+)DKD(-) groups than in the DR(-)DKD(-) group. The results for vision-threatening DR and advanced DKD were similar. The interaction for non-cancer non-vascular mortality, but not all-cause and vascular mortality, between DR and DKD and between vision-threatening DR and advanced DKD might be significant.

CONCLUSIONS

DR and DKD may be jointly and independently associated with all-cause, vascular and non-cancer non-vascular mortality, but not cancer mortality, according to their severity in real-world patients with type 2 diabetes.

Effect of postprandial hyperglycemia at clinic visits on the incidence of retinopathy in patients with type 2 diabetes: An analysis using real-world long-term follow-up data

AIMS/INTRODUCTION

There is little evidence on the role of postprandial glycemia in the incidence of diabetic retinopathy (DR) in a real-world setting. We aimed to assess the effect of postprandial hyperglycemia at clinic visits on the incidence of DR in patients with type 2 diabetes, and whether its effect differs depending on glycated hemoglobin (HbA1c) values and age.

MATERIALS AND METHODS

Intrapersonal mean blood glucose levels at 1-2 h post-breakfast (1-2h-PBBG), post-lunch (1-2 h-PLBG) and both (1-2h-PBLBG) during 2 years from the first visit were used as baseline data. This retrospective cohort study enrolled 487, 323 and 406 patients who had 1-2h-PBLBG, 1-2h-PBBG and 1-2h-PLBG measurements, respectively. These three groups were followed from 1999 up through 2017.

RESULTS

DR occurred in 145, 92 and 126 patients in the 1-2h-PBLBG, 1-2h-PBBG and 1-2h-PLBG groups, respectively. Multivariate Cox regression analysis showed that the mean 1-2h-PBLBG, 1-2h-PBBG and 1-2h-PLBG levels were significant predictors of DR, independent of mean HbA1c. In patients with mean HbA1c <7.0% and those with a baseline age <60 years, the mean 1-2h-PBLBG, 1-2h-PBBG and 1-2h-PLBG levels were significant predictors.

CONCLUSIONS

Postprandial hyperglycemia at clinic visits might predict the incidence of DR, independent of HbA1c. The effect of postprandial hyperglycemia on DR is obvious in patients with well-controlled HbA1c and in younger patients. Even with the lower HbA1c level, correcting postprandial hyperglycemia is important for preventing DR, especially in middle-aged adults with type 2 diabetes.

The PDK1-FoxO1 signaling in adipocytes controls systemic insulin sensitivity through the 5-lipoxygenase-leukotriene B4 axis

Although adipocytes are major targets of insulin, the influence of impaired insulin action in adipocytes on metabolic homeostasis remains unclear. We here show that adipocyte-specific PDK1 (3'-phosphoinositide-dependent kinase 1)-deficient (A-PDK1KO) mice manifest impaired metabolic actions of insulin in adipose tissue and reduction of adipose tissue mass. A-PDK1KO mice developed insulin resistance, glucose intolerance, and hepatic steatosis, and this phenotype was suppressed by additional ablation of FoxO1 specifically in adipocytes (A-PDK1/FoxO1KO mice) without an effect on adipose tissue mass. Neither circulating levels of adiponectin and leptin nor inflammatory markers in adipose tissue differed between A-PDK1KO and A-PDK1/FoxO1KO mice. Lipidomics and microarray analyses revealed that leukotriene B4 (LTB4) levels in plasma and in adipose tissue as well as the expression of 5-lipoxygenase (5-LO) in adipose tissue were increased and restored in A-PDK1KO mice and A-PDK1/FoxO1KO mice, respectively. Genetic deletion of the LTB4 receptor BLT1 as well as pharmacological intervention to 5-LO or BLT1 ameliorated insulin resistance in A-PDK1KO mice. Furthermore, insulin was found to inhibit LTB4 production through down-regulation of 5-LO expression via the PDK1-FoxO1 pathway in isolated adipocytes. Our results indicate that insulin signaling in adipocytes negatively regulates the production of LTB4 via the PDK1-FoxO1 pathway and thereby maintains systemic insulin sensitivity.

GCN2 regulates pancreatic β cell mass by sensing intracellular amino acid levels

EIF2AK4, which encodes the amino acid deficiency-sensing protein GCN2, has been implicated as a susceptibility gene for type 2 diabetes in the Japanese population. However, the mechanism by which GCN2 affects glucose homeostasis is unclear. Here, we show that insulin secretion is reduced in individuals harboring the risk allele of EIF2AK4 and that maintenance of GCN2-deficient mice on a high-fat diet results in a loss of pancreatic β cell mass. Our data suggest that GCN2 senses amino acid deficiency in β cells and limits signaling by mechanistic target of rapamycin complex 1 to prevent β cell failure during the consumption of a high-fat diet.

Podocyte-specific deletion of tubular sclerosis complex 2 promotes focal segmental glomerulosclerosis and progressive renal failure

Obesity can initiate and accelerate the progression of kidney diseases. However, it remains unclear how obesity affects renal dysfunction. Here, we show that a newly generated podocyte-specific tubular sclerosis complex 2 (Tsc2) knockout mouse model (Tsc2Δpodocyte) develops proteinuria and dies due to end-stage renal dysfunction by 10 weeks of age. Tsc2Δpodocyte mice exhibit an increased glomerular size and focal segmental glomerulosclerosis, including podocyte foot process effacement, mesangial sclerosis and proteinaceous casts. Podocytes isolated from Tsc2Δpodocyte mice show nuclear factor, erythroid derived 2, like 2-mediated increased oxidative stress response on microarray analysis and their autophagic activity is lowered through the mammalian target of rapamycin (mTOR)-unc-51-like kinase 1 pathway. Rapamycin attenuated podocyte dysfunction and extends survival in Tsc2Δpodocyte mice. Additionally, mTOR complex 1 (mTORC1) activity is increased in podocytes of renal biopsy specimens obtained from obese patients with chronic kidney disease. Our work shows that mTORC1 hyperactivation in podocytes leads to severe renal dysfunction and that inhibition of mTORC1 activity in podocytes could be a key therapeutic target for obesity-related kidney diseases.

Hepatic Gluconeogenic Response to Single and Long-Term SGLT2 Inhibition in Lean/Obese Male Hepatic G6pc-Reporter Mice

Sodium-glucose cotransporter 2 inhibitor (SGLT2i) consistently reduces blood glucose levels in type 2 diabetes mellitus but increases hepatic gluconeogenic gene expression and glucose production, offsetting its glucose-lowering effect. This study aimed to elucidate the effect of SGLT2i on hepatic gluconeogenic response and its mechanism in both insulin-sensitive and insulin-resistant states. A hepatic mouse model was generated to show liver-specific expression of Gaussia luciferase (GLuc) driven by the gluconeogenic enzyme gene G6pc promoter. Hepatic gluconeogenic response was evaluated by measuring plasma GLuc activity. SGLT2i was given to lean and obese mice in single gavage administration or 4-week dietary administration with controlled feeding every 3 hours. In lean mice, single-dose SGLT2i increased plasma GLuc activity from 2 hours after administration, decreasing blood glucose and plasma insulin from 1 to 2 hours after administration. In obese mice, which had higher plasma GLuc activity than lean ones, SGLT2i did not further increase GLuc activity despite decreased blood glucose and plasma insulin. Hepatic Akt and GSK3β phosphorylation was attenuated by single-dose SGLT2i in lean mice in accordance with the plasma insulin decrease, but not in obese mice. Long-term SGLT2i administration, which increased plasma GLuc activity in lean mice, decreased it in obese mice from 3 weeks after initiation, with increased hepatic Akt and GSK3β phosphorylation. In conclusion, single SGLT2i administration increases hepatic gluconeogenic response in lean insulin-sensitive mice, but not in obese insulin-resistant mice. Long-term SGLT2i administration relieves obesity-induced upregulation of the hepatic gluconeogenic response by restoring impeded hepatic insulin signaling in obese insulin-resistant mice.

Analysis of the duration and extent of the legacy effect in patients with type 2 diabetes: A real-world longitudinal study

AIMS

To analyze the duration and extent of the legacy effect on diabetic complications in real-world patients with type 2 diabetes.

METHODS

This was a retrospective cohort study. We included the following three cohorts of patients: diabetic retinopathy (DR) (n = 1107), diabetic kidney disease (DKD) (n = 1486), and cardiovascular disease (CVD) (n = 1485). Patients were enrolled from 1995 to 1999 and followed up to 2017. Endpoints were DR incidence, ≥40% decrease in estimated glomerular filtration rate, and CVD incidence. The relationships between HbA1c as a time-dependent variable and the risk of reaching each endpoint were analyzed using multivariate Cox regression models.

RESULTS

A total of 313 patients developed DR, 316 developed DKD, and 177 developed CVD. Hazard ratios as a function of time-dependent HbA1c (moving mean) accumulated over time. This accumulation was largest for DR, followed by DKD and CVD. The hazard ratios for each endpoint reached a plateau during the preceding 14-19 years.

CONCLUSIONS

The effect of past glycemic control may continue during 14-19 years, with a greater effect during ≤10 years. Therefore, the end of the legacy effect could be 15-20 years. This effect may be the greatest for DR, followed by DKD, and the smallest for CVD.

Diabetes Care Providers' Manual for Disaster Diabetes Care

To ensure that experiences and lessons learned from the unprecedented 2011 Great East Japan Earthquake are used to improve future disaster planning, the Japan Diabetes Society (JDS) launched the "Research and Survey Committee for Establishing Disaster Diabetes Care Systems Based on Relevant Findings from the Great East Japan Earthquake" under the supervision of the Chairman of the JDS. The Committee conducted a questionnaire survey among patients with diabetes, physicians, disaster medical assistance teams (DMATs), nurses, pharmacists, and nutritionists in disaster areas about the events they saw happening, the situations they found difficult to handle, and the needs that they felt required to be met during the 2011 Great East Japan Earthquake. A total of 3,481 completed questionnaires were received. Based on these and other experiences and lessons reported following the 2011 Great East Japan Earthquake and the 2004 Niigata-Chuetsu Earthquakes, the current "Manual for Disaster Diabetes Care" has been developed by the members of the Committee and other invited authors from relevant specialties. To our knowledge, the current Manual is the world's first to focus on emergency diabetes care, with this digest English version translated from the Japanese original. It is sincerely hoped that patients with diabetes and healthcare providers around the world will find this manual helpful in promoting disaster preparedness and implementing disaster relief.

Design of and rationale for the Japan Diabetes compREhensive database project based on an Advanced electronic Medical record System (J-DREAMS)

The "Japan Diabetes compREhensive database project based on an Advanced electronic Medical record System" is a registry of patients with diabetes in Japan. The characteristics of this registry include a clinical information input process using the template function of an electronic medical record (EMR) system [the standard diabetes management template (SDMT)], a standardized exchangeable information storage format [the Standardized Structured Medical Information eXchange 2 (SS-MIX2)], and a secure and efficient information extraction process [Multipurpose Clinical Data Repository System (MCDRS)]. Together, these characteristics enable efficient data input during routine patient consultations, efficient and exact data extraction from each facility, and the integration of data across different facilities even though these data were generated by EMR systems from different vendors. The SDMT collects clinical information including the type of diabetes, body height and weight, blood pressure, lifestyle, and comorbidities. Completing this template triggers the automatic collection of other information such as fundamental information (sex, year and month of birth, and facility), prescription information, and laboratory examination results. As the information from every routine consultation is saved with an anonymized patient ID, linked data can be used as panel data allowing longitudinal investigations. The data obtained from the registry will allow analyses, for exmaple, mortality and morbidity risk, by various characteristics or drug types and may reveal unmet needs that inform future diabetes care.

New glycemic targets for patients with diabetes from the Japan Diabetes Society

In the 'Evidence-based Practice Guideline for the Treatment for Diabetes in Japan 2013', a new concept of the glycemic control in patients with diabetes in Japan has been declared from the Japan Diabetes Society. The main objective value of HbA1c was set to <7% from the perspective of preventing microvascular complications. On the other hand, the objective in cases where objectives can be attained by appropriate dietary or exercise therapy, or during pharmacotherapy without the occurrence of side effects such as hypoglycemia was set to <6%, and the objective in cases where intensification of treatment was considered difficult due to side effects such as hypoglycemia or for other reasons was set to <8%. Treatment objectives should be established individually, in consideration of age, duration of disease, organ damage, risk of hypoglycemia, support structure, and etc.

The GCN5-CITED2-PKA signalling module controls hepatic glucose metabolism through a cAMP-induced substrate switch

Hepatic gluconeogenesis during fasting results from gluconeogenic gene activation via the glucagon-cAMP-protein kinase A (PKA) pathway, a process whose dysregulation underlies fasting hyperglycemia in diabetes. Such transcriptional activation requires epigenetic changes at promoters by mechanisms that have remained unclear. Here we show that GCN5 functions both as a histone acetyltransferase (HAT) to activate fasting gluconeogenesis and as an acetyltransferase for the transcriptional co-activator PGC-1α to inhibit gluconeogenesis in the fed state. During fasting, PKA phosphorylates GCN5 in a manner dependent on the transcriptional coregulator CITED2, thereby increasing its acetyltransferase activity for histone and attenuating that for PGC-1α. This substrate switch concomitantly promotes both epigenetic changes associated with transcriptional activation and PGC-1α-mediated coactivation, thereby triggering gluconeogenesis. The GCN5-CITED2-PKA signalling module and associated GCN5 substrate switch thus serve as a key driver of gluconeogenesis. Disruption of this module ameliorates hyperglycemia in obese diabetic animals, offering a potential therapeutic strategy for such conditions.

Report of the Japan diabetes society/Japanese cancer association joint committee on diabetes and cancer, Second report

The Japan Diabetes Society/Japanese Cancer Association Joint Committee on Diabetes and Cancer published its first report in July 2013 on the epidemiological assessment of the associations of diabetes with cancer risk/prognosis, the common risk factors for diabetes and cancer, and cancer risk associated with diabetes treatment. The Joint Committee continued its work to assess the role of glycemic control in the development of cancer in patients with diabetes. This review shows that high‐quality evidence examining the association between glycemic control and cancer risk is lacking.

In 2014, the Japan Diabetes Society (JDS) and the Japanese Cancer Association (JCA) restarted the JDS/JCA Joint Committee on Diabetes and Cancer, which published the second committee report in Japanese [1]. This is the English version of that report. This article has been jointly published in Diabetology International (doi:10.1007/s13340‐016‐0257‐z) and Cancer Science by the Japan Diabetes Society and the Japanese Cancer Association.

Members of the JDS/JCA Joint Committee on Diabetes and Cancer. JDS: Mitsuhiko Noda, Kohjiro Ueki, Masato Kasuga, Naoko Tajima, and Ken Ohashi; Editorial collaborators: Atsushi Goto and Hiroshi Noto; JCA: Ryuichi Sakai, Shoichiro Tsugane, Nobuyuki Hamajima, Kazuo Tajima, Kohzoh Imai, and Hitoshi Nakagama.

Report of the Japan Diabetes Society (JDS)/Japanese Cancer Association (JCA) Joint Committee on Diabetes and Cancer, Second Report

The Japan Diabetes Society (JDS)/Japanese Cancer Association (JCA) Joint Committee on Diabetes and Cancer published its first report in July 2013 on the epidemiological assessment of the associations of diabetes with cancer risk/prognosis, the common risk factors for diabetes and cancer, and cancer risk associated with diabetes treatment The JDS/JCA Joint Committee continued its work to assess the role of glycemic control in the development of cancer in patients with diabetes. This review shows that high-quality evidence examining the association between glycemic control and cancer risk is lacking.

Efficacy and safety of 40 mg or 60 mg duloxetine in Japanese adults with diabetic neuropathic pain: Results from a randomized, 52-week, open-label study

Introduction

To examine the long‐term efficacy and safety of duloxetine in the treatment of Japanese patients with diabetic neuropathic pain, we carried out a 52‐week, randomized, open‐label extension of a 12‐week, double‐blind, placebo‐controlled study.

Materials and Methods

Japanese adults with diabetic neuropathic pain who completed the double‐blind study were eligible for this long‐term study, carried out at 71 sites in Japan (March 2008 to March 2010). Participants (n = 258) were re‐randomized (1:1) to 40 mg/day or 60 mg/day duloxetine. Pain (Brief Pain Inventory severity and interference), quality of life (Patient's Global Impression of Improvement), and safety (primary outcome; adverse events, vital signs, metabolic measures) were measured.

Results

Significant (P < 0.0001) and sustained improvements (change ± standard deviation; n = 257) were observed in Brief Pain Inventory severity (average pain score −2.1 ± 1.7). Improvements were also seen in Brief Pain Inventory interference (mean of subscores −0.96 ± 1.52) and Patient's Global Impression of Improvement (−0.9 ± 1.1) scores; these scores decreased significantly (P < 0.0001) during the long‐term study. Frequently reported adverse events included somnolence (13.6%), constipation (13.2%) and nausea (10.5%). Increases were observed in plasma glucose, glycosylated hemoglobin and total cholesterol levels, and in bodyweight and heart rate; however, none of these were clinically meaningful. Overall, there were no clinically significant safety concerns.

Conclusions

This is the first publication of a long‐term study carried out in Asia with an entirely Japanese patient population to suggest that long‐term duloxetine therapy for diabetic neuropathic pain is effective and has an acceptable safety profile.

Growth arrest and DNA damage-inducible 34 regulates liver regeneration in hepatic steatosis in mice

The liver has robust regenerative potential in response to damage, but hepatic steatosis (HS) weakens this potential. We found that the enhanced integrated stress response (ISR) mediated by phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2α) impairs regeneration in HS and that growth arrest and DNA damage-inducible 34 (Gadd34)-dependent suppression of ISR plays a crucial role in fatty liver regeneration. Although mice fed a high-fat diet for 2 weeks developed moderate fatty liver with no increase in eIF2α phosphorylation before 70% hepatectomy, they showed impaired liver regeneration as a result of reduced proliferation and increased death of hepatocytes with increased phosphorylation of eIF2α and ISR. An increased ISR through Gadd34 knockdown induced C/EBP homologous protein (CHOP)-dependent apoptosis and receptor-interacting protein kinase 3-dependent necrosis, resulting in increased hepatocyte death during fatty liver regeneration. Furthermore, Gadd34 knockdown and increased phosphorylation of eIF2α decreased cyclin D1 protein and reduced hepatocyte proliferation. In contrast, enhancement of Gadd34 suppressed phosphorylation of eIF2α and reduced CHOP expression and hepatocyte apoptosis without affecting hepatocyte proliferation, clearly improving fatty liver regeneration. In more severe fatty liver of leptin receptor-deficient db/db mice, forced expression of hepatic Gadd34 also promoted hepatic regeneration after hepatectomy.

CONCLUSION

Gadd34-mediated regulation of ISR acts as a physiological defense mechanism against impaired liver regeneration resulting from steatosis and is thus a possible therapeutic target for impaired regeneration in HS.

Establishment of maturity-onset diabetes of the young-induced pluripotent stem cells from a Japanese patient

Maturity-onset diabetes of the young (MODY) is a heterozygous monogenic diabetes; more than 13 disease genes have been identified. However, the pathogenesis of MODY is not fully understood, because the pancreatic β-cells of the patients are inaccessable. Therefore, we attempted to establish MODY patient-derived induced pluripotent stem cells (MODY-iPS) cells to investigate the pathogenic mechanism of MODY by inducing pancreatic β-cells. We established MODY5-iPS cells from a Japanese patient with MODY5 (R177X), and confirmed that MODY5-iPS cells possessed the characteristics of pluripotent stem cells. In the course of differentiation from MODY5-iPS cells into pancreatic β-cells, we examined the disease gene, HNF1B messenger ribonucleic acid. We found that the amount of R177X mutant transcripts was much less than that of wild ones, but they increased after adding cycloheximide to the medium. These results suggest that these R177X mutant messenger ribonucleic acids are disrupted by nonsense-mediated messenger ribonucleic acid decay in MODY-iPS cells during the developmental stages of pancreatic β-cells.

Causes of death in Japanese diabetics: A questionnaire survey of 18,385 diabetics over a 10-year period

We collated and analysed data from hospital records regarding the cause of death of 18,385 patients with diabetes who died in 282 medical institutions throughout Japan over the 10‐year period between 1991 and 2000. Autopsy was carried out in 1750 cases. The most frequent cause of death in all 18,385 cases was malignant neoplasia, accounting for 34.1% of cases, followed by vascular diseases (including diabetic nephropathy, ischemic heart diseases and cerebrovascular diseases) in 26.8%, infections in 14.3%, and then diabetic coma in 1.2%. The most common malignancy was liver cancer, accounting for 8.6% of all the deaths. Of the deaths from vascular diseases, diabetic nephropathy was the cause of death in 6.8% of cases, and the frequency as cause of death for ischemic heart diseases and cerebrovascular diseases were similar at 10.2% and 9.8%, respectively. Myocardial infarction accounted for almost all the deaths from ischemic heart diseases, whereas deaths from cerebral infarction were 2.2‐fold as common as those from cerebral hemorrhage. In the analyses of the relationship between age and causes of death in diabetic patients who underwent autopsy, the overall mortality rate as a result of vascular diseases increased with age, although the mortality rates from diabetic nephropathy and cerebrovascular diseases increased little from the fifth decade of life. The mortality rate from ischemic heart diseases increased with age, however, and was higher than the other forms of vascular diseases from the sixth decade of life, accounting for approximately 50% of vascular deaths in the eighth decade. Malignant neoplasia was the most frequent cause of death from the fifth decade of life, and was extremely common in the seventh decade, accounting for 46.3% of all the deaths. The mortality rate from infections varied little between age groups from the fifth decade of life. In the analyses of glycemic control and the age at the time of death, lifespans were 2.5 years shorter in males, and 1.6 years shorter in female diabetics with poor glycemic control than in those with good or fair glycemic control. This difference was greater for deaths as a result of infections and vascular diseases, particularly diabetic nephropathy, than for malignant neoplasia. Analysis of the relationship between glycemic control and the duration of diabetes and deaths as a result of vascular diseases showed no correlation between the level of glycemic control and death from diabetic nephropathy, ischemic heart diseases or cerebrovascular diseases. In diabetics with disease durations of less than 10 years, the mortality rate from macroangiopathy was higher than that as a result of diabetic nephropathy, a form of microangiopathy. Treatment for diabetes comprised of diet alone in 21.5%, oral hypoglycemic agents in 29.5%, and insulin with or without oral hypoglycemic agents in 44.2%, which was the most common. In particular, 683/1170 (58.4%) diabetics who died from diabetic nephropathy were on insulin therapy, a higher proportion than the 661/1687 (39.2%) who died from ischemic heart diseases, or the 659/1622 (40.6%) who died from cerebrovascular diseases. The average age at the time of death in the survey population was, 68 years for males and 71.6 years for females. These were 9.6 and 13 years, respectively, short of the average life expectancy for the Japanese general population. In comparison with the previous survey (1981–1990), the average age at the time of death had increased 1.5 years for males, and 3.2 years for females. The average life expectancy for the Japanese general population had also increased 1.7 and 2.7 years, respectively, over that period, showing that advances in the management and treatment of diabetes have not led to any improvement in patients’ life expectancies. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00019.x, 2010)

Superiority of duloxetine to placebo in improving diabetic neuropathic pain: Results of a randomized controlled trial in Japan

Aims/Introduction:  Duloxetine has been suggested to exert analgesic effects by activating the descending inhibitory system through inhibition of serotonin (5‐HT) and noradrenaline (NA) reuptake. This randomized controlled trial investigated the efficacy and safety of duloxetine in Japanese patients with diabetic neuropathic pain (DNP).

Materials and Methods:  Duloxetine 40 or 60 mg/day or placebo was given orally once daily for 12 weeks. The primary efficacy measure was weekly mean 24‐h average pain severity score on the 11‐point Numerical Rating Scale.

Results:  At 12 weeks vs baseline, the 24‐h average pain score (adjusted mean ± SE) was significantly improved in the combined duloxetine (−2.47 ± 0.18) and duloxetine 40 mg (−2.41 ± 0.21) and 60 mg groups (−2.53 ± 0.21) as compared with the placebo group (−1.61 ± 0.18). Duloxetine also exerted significant improvements over the placebo in nearly all secondary outcome measures including 24‐h worst pain, night pain, Brief Pain Inventory (BPI) pain scores, Patient’s Global Impression of Improvement (PGI‐I) and health outcome measures, namely, various BPI interference scores. The incidence of adverse events (AE) was higher in the duloxetine groups than in the placebo group (duloxetine overall, 84.8%; duloxetine 40 mg, 84.7%; duloxetine 60 mg, 84.9%; placebo, 73.7%). Most AE were mild or moderate in severity, and resolved or relieved. There were no clinically significant safety concerns.

Conclusions:  Duloxetine 40 or 60 mg/day showed superiority over the placebo at reducing pain scores in patients with DNP. Duloxetine is safe, efficacious and clinically useful in the management of DNP. This trial was registered with ClinicalTrials.gov (no. NCT‐00552175). (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00073.x, 2010)

Report of the Japan Diabetes Society/Japanese Cancer Association Joint Committee on Diabetes and Cancer

In recent years, diabetes has been shown to be associated with cancer risk, and this has led to a joint committee being formed, enlisting experts from the Japan Diabetes Society and the Japanese Cancer Association to address this issue. Epidemiological data in Japan provides evidence to demonstrate that diabetes is associated with increased risk for cancers, especially colorectal, liver, and pancreatic cancers. The mechanisms through which diabetes is assumed to promote oncogenesis include insulin resistance and associated hyperinsulinemia, hyperglycemia, and inflammation. Common risk factors for type 2 diabetes and cancer include aging, male sex, obesity, physical inactivity, inappropriate diet (excessive red/processed meat intake, inadequate vegetable/fruit/dietary fiber intake), excessive alcohol drinking, and smoking. Given that inappropriate diet/exercise, smoking and excessive alcohol drinking are common risk factors for diabetes and cancer, diet/exercise therapy, smoking cessation and alcohol moderation may be associated with decreased risk for cancer in diabetic patients. There is as yet limited evidence as to whether any particular antidiabetic agents may influence cancer risk.

Histidine augments the suppression of hepatic glucose production by central insulin action

Glucose intolerance in type 2 diabetes is related to enhanced hepatic glucose production (HGP) due to the increased expression of hepatic gluconeogenic enzymes. Previously, we revealed that hepatic STAT3 decreases the expression of hepatic gluconeogenic enzymes and suppresses HGP. Here, we show that increased plasma histidine results in hepatic STAT3 activation. Intravenous and intracerebroventricular (ICV) administration of histidine-activated hepatic STAT3 reduced G6Pase protein and mRNA levels and augmented HGP suppression by insulin. This suppression of hepatic gluconeogenesis by histidine was abolished by hepatic STAT3 deficiency or hepatic Kupffer cell depletion. Inhibition of HGP by histidine was also blocked by ICV administration of a histamine H1 receptor antagonist. Therefore, histidine activates hepatic STAT3 and suppresses HGP via central histamine action. Hepatic STAT3 phosphorylation after histidine ICV administration was attenuated in histamine H1 receptor knockout (Hrh1KO) mice but not in neuron-specific insulin receptor knockout (NIRKO) mice. Conversely, hepatic STAT3 phosphorylation after insulin ICV administration was attenuated in NIRKO but not in Hrh1KO mice. These findings suggest that central histidine action is independent of central insulin action, while both have additive effects on HGP suppression. Our results indicate that central histidine/histamine-mediated suppression of HGP is a potential target for the treatment of type 2 diabetes.

Ras-related C3 botulinum toxin substrate 1 (RAC1) regulates glucose-stimulated insulin secretion via modulation of F-actin

AIMS/HYPOTHESIS

The small G-protein ras-related C3 botulinum toxin substrate 1 (RAC1) plays various roles in mammalian cells, such as in the regulation of cytoskeletal organisation, cell adhesion, migration and morphological changes. The present study examines the effects of RAC1 ablation on pancreatic beta cell function.

METHODS

Isolated islets from pancreatic beta cell-specific Rac1-knockout (betaRac1(-/-)) mice and RAC1 knockdown INS-1 insulinoma cells treated with small interfering RNA were used to investigate insulin secretion and cytoskeletal organisation in pancreatic beta cells.

RESULTS

BetaRac1(-/-) mice showed decreased glucose-stimulated insulin secretion, while there were no apparent differences in islet morphology. Isolated islets from the mice had blunted insulin secretion in response to high glucose levels. In RAC1 knockdown INS-1 cells, insulin secretion was also decreased in response to high glucose levels, consistent with the phenotype of betaRac1(-/-) mice. Even under high glucose levels, RAC1 knockdown INS-1 cells remained intact with F-actin, which inhibits the recruitment of the insulin granules, resulting in an inhibition of insulin secretion.

CONCLUSIONS/INTERPRETATION

In RAC1-deficient pancreatic beta cells, F-actin acts as a barrier for insulin granules and reduces glucose-stimulated insulin secretion.

Decreased serum chemerin levels in male Japanese patients with type 2 diabetes: sex dimorphism

Chemerin, a recently discovered adipocytokine plays an important role in obesity and obesity-associated metabolic complications. However, the role of chemerin in the pathogenesis of type 2 diabetes mellitus (T2DM) has not fully been elucidated. We compared the serum chemerin levels and metabolic parameters between 88 control subjects, 86 patients with metabolic syndrome (MS), and 147 patients with T2DM in a Japanese population and further analyzed their correlation. Enzyme-linked immunosorbent assay was used to measure the serum chemerin levels. The chemerin levels were significantly higher in male than in female control subjects (p < 0.005), with significant decreases in patients with T2DM compared with those with MS and control subjects (164.9 ± 6.3 ng/mL vs. 209.8 ± 7.7 and 218.7 ± 7.3 ng/mL; p < 0.0001 vs. p < 0.0001, respectively) but no significant differences in female subjects. The multiple regression analysis revealed that the chemerin levels negatively correlated with the fasting glucose and HbA1c levels in total and male subjects. In the patients with T2DM, the chemerin levels negatively correlated with fasting glucose and high-density lipoprotein cholesterol but positively correlated with body mass index (BMI), and total cholesterol and triglyceride levels. The negative correlation between the chemerin and fasting glucose levels remained significant after adjustment for age, sex, and BMI in the total and male subjects and those with T2DM. These results suggest the role of chemerin in sex dimorphism and a potential link between chemerin levels and T2DM pathogenesis in a Japanese population.

Loss of Pdk1-Foxo1 signaling in myeloid cells predisposes to adipose tissue inflammation and insulin resistance

Chronic inflammation in adipose tissue contributes to obesity-related insulin resistance. The 3-phosphoinositide-dependent protein kinase 1 (Pdk1)/forkhead transcription factor (Foxo1) pathway is important in regulating glucose and energy homeostasis, but little is known about this pathway in adipose tissue macrophages (ATMs). To investigate this, we generated transgenic mice that carried macrophage/granulocyte-specific mutations, including a Pdk1 knockout (LysMPdk1(-/-)), a Pdk1 knockout with transactivation-defective Foxo1 (Δ256LysMPdk1(-/-)), a constitutively active nuclear (CN) Foxo1 (CNFoxo1(LysM)), or a transactivation-defective Foxo1 (Δ256Foxo1(LysM)). We analyzed glucose metabolism and gene expression in ATM populations isolated with fluorescence-activated cell sorting. The LysMPdk1(-/-) mice exhibited elevated M1 macrophages in adipose tissue and insulin resistance. Overexpression of transactivation-defective Foxo1 rescued these phenotypes. CNFoxo1(LysM) promoted transcription of the C-C motif chemokine receptor 2 (Ccr2) in ATMs and increased M1 macrophages in adipose tissue. On a high-fat diet, CNFoxo1(LysM) mice exhibited insulin resistance. Pdk1 deletion or Foxo1 activation in bone marrow-derived macrophages abolished insulin and interleukin-4 induction of genes involved in alternative macrophage activation. Thus, Pdk1 regulated macrophage infiltration by inhibiting Foxo1-induced Ccr2 expression. This shows that the macrophage Pdk1/Foxo1 pathway is important in regulating insulin sensitivity in vivo.

A single-nucleotide polymorphism in ANK1 is associated with susceptibility to type 2 diabetes in Japanese populations

To identify a novel susceptibility locus for type 2 diabetes, we performed an imputation-based, genome-wide association study (GWAS) in a Japanese population using newly obtained imputed-genotype data for 2 229 890 single-nucleotide polymorphisms (SNPs) estimated from previously reported, directly genotyped GWAS data in the same samples (stage 1: 4470 type 2 diabetes versus 3071 controls). We directly genotyped 43 new SNPs with P-values of <10(-4) in a part of stage-1 samples (2692 type 2 diabetes versus 3071 controls), and the associations of validated SNPs were evaluated in another 11 139 Japanese individuals (stage 2: 7605 type 2 diabetes versus 3534 controls). Combined meta-analysis using directly genotyped data for stages 1 and 2 revealed that rs515071 in ANK1 and rs7656416 near MGC21675 were associated with type 2 diabetes in the Japanese population at the genome-wide significant level (P < 5 × 10(-8)). The association of rs515071 was also observed in European GWAS data (combined P for all populations = 6.14 × 10(-10)). Rs7656416 was in linkage disequilibrium to rs6815464, which had recently been identified as a top signal in a meta-analysis of East Asian GWAS for type 2 diabetes (r(2) = 0.76 in stage 2). The association of rs7656416 with type 2 diabetes disappeared after conditioning on rs6815464. These results indicate that the ANK1 locus is a new, common susceptibility locus for type 2 diabetes across different ethnic groups. The signal of association was weaker in the directly genotyped data, so the improvement in signal indicates the importance of imputation in this particular case.

Endoplasmic reticulum stress inhibits STAT3-dependent suppression of hepatic gluconeogenesis via dephosphorylation and deacetylation

In the liver, signal transducer and activator of transcription 3 (STAT3) plays an important role in the suppression of gluconeogenic enzyme expression. While obesity-associated endoplasmic reticulum (ER) stress has been shown to increase hepatic gluconeogenic enzyme expression, the role of ER stress in STAT3-dependent regulation of such expression is unclear. The current study aimed to elucidate the effect of ER stress on the STAT3-dependent regulation of hepatic gluconeogenic enzyme expression. Genetically obese/diabetic db/db mice and db/db mouse-derived isolated hepatocytes were used as ER stress models. A tyrosine phosphatase inhibitor, a deacetylation inhibitor, and an acetylated mutant of STAT3 were used to examine the effect of ER stress on hepatic STAT3 action. ER stress inhibited STAT3-dependent suppression of gluconeogenic enzyme gene expression by suppressing hepatic Janus kinase (JAK)2 and STAT3 phosphorylation. A tyrosine phosphatase inhibitor restored ER stress-induced suppression of JAK2 phosphorylation but exhibited no improving effect on suppressed STAT3 phosphorylation. STAT3 acetylation is known to correlate with its phosphorylation. ER stress also decreased STAT3 acetylation. An acetylated mutant of STAT3 was resistant to ER stress-induced inhibition of STAT3-phosphorylation and STAT3-dependent suppression of hepatic gluconeogenic enzyme gene expression in vitro and in vivo. Trichostatin A, a histone deacetylase (HDAC) inhibitor, ameliorated ER stress-induced inhibition of STAT3 acetylation and phosphorylation. The current study revealed that ER stress inhibits STAT3-dependent suppression of hepatic gluconeogenic enzymes via JAK2 dephosphorylation and HDAC-dependent STAT3 deacetylation, playing an important role in the increase of hepatic glucose production in obesity and diabetes.

Administration of BMP2/7 in utero partially reverses Rubinstein-Taybi syndrome-like skeletal defects induced by Pdk1 or Cbp mutations in mice

Mutations in the coactivator CREB-binding protein (CBP) are a major cause of the human skeletal dysplasia Rubinstein-Taybi syndrome (RTS); however, the mechanism by which these mutations affect skeletal mineralization and patterning is unknown. Here, we report the identification of 3-phosphoinositide-dependent kinase 1 (PDK1) as a key regulator of CBP activity and demonstrate that its functions map to both osteoprogenitor cells and mature osteoblasts. In osteoblasts, PDK1 activated the CREB/CBP complex, which in turn controlled runt-related transcription factor 2 (RUNX2) activation and expression of bone morphogenetic protein 2 (BMP2). These pathways also operated in vivo, as evidenced by recapitulation of RTS spectrum phenotypes with osteoblast-specific Pdk1 deletion in mice (Pdk1osx mice) and by the genetic interactions observed in mice heterozygous for both osteoblast-specific Pdk1 deletion and either Runx2 or Creb deletion. Finally, treatment of Pdk1osx and Cbp+/- embryos with BMPs in utero partially reversed their skeletal anomalies at birth. These findings illustrate the in vivo function of the PDK1-AKT-CREB/CBP pathway in bone formation and provide proof of principle for in utero growth factor supplementation as a potential therapy for skeletal dysplasias.