Efficacy of StepAdd, a Personalized mHealth Intervention Based on Social Cognitive Theory to Increase Physical Activity Among Patients With Type 2 Diabetes Mellitus: Protocol for a Randomized Controlled Trial

BACKGROUND

Increasing physical activity improves glycemic control in patients with type 2 diabetes (T2D). Mobile health (mHealth) interventions have been proven to increase exercise, but engagement often fades with time. As the use of health behavior theory in mHealth design can increase effectiveness, we developed StepAdd, an mHealth intervention based on the constructs of social cognitive theory (SCT). StepAdd improves exercise behavior self-efficacy and self-regulation through the use of goal-setting, barrier-identifying, and barrier-coping strategies, as well as automatic feedback functions. A single-arm pilot study of StepAdd among 33 patients with T2D showed a large increase in step count (mean change of 4714, SD 3638 daily steps or +86.7%), along with strong improvements in BMI (mean change of -0.3 kg/m2) and hemoglobin A1c level (mean change of -0.79 percentage points).

OBJECTIVE

In this study, we aim to investigate the efficacy and safety of StepAdd, an mHealth exercise support system for patients with T2D, via a large, long, and controlled follow-up to the pilot study.

METHODS

This is a randomized, open-label, multicenter study targeting 160 patients with T2D from 5 institutions in Japan with a 24-week intervention. The intervention group will record daily step counts, body weight, and blood pressure using the SCT-based mobile app, StepAdd, and receive feedback about these measurements. In addition, they will set weekly step count goals, identify personal barriers to walking, and define strategies to overcome these barriers. The control group will record daily step counts, body weight, and blood pressure using a non-SCT-based placebo app. Both groups will receive monthly consultations with a physician who will advise patients regarding lifestyle modifications and use of the app. The 24-week intervention period will be followed by a 12-week observational period to investigate the sustainability of the intervention's effects. The primary outcome is between-group difference in the change in hemoglobin A1c values at 24 weeks. The secondary outcomes include other health measures, measurements of steps, measurements of other behavior changes, and assessments of app use. The trial began in January 2023 and is intended to be completed in December 2025.

RESULTS

As of September 5, 2023, we had recruited 44 patients. We expect the trial to be completed by October 8, 2025, with the follow-up observation period being completed by December 31, 2025.

CONCLUSIONS

This trial will provide important evidence about the efficacy of an SCT-based mHealth intervention in improving physical activities and glycemic control in patients with T2D. If this study proves the intervention to be effective and safe, it could be a key step toward the integration of mHealth as part of the standard treatment received by patients with T2D in Japan.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (JRCT) jRCT2032220603; https://rctportal.niph.go.jp/en/detail?trial_id=jRCT2032220603.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/53514.

Effects of hybrid closed-loop system on glycemic control and psychological aspects in persons with type 1 diabetes treated with sensor-augmented pump: A prospective single-center observational study

AIMS/INTRODUCTION

This study evaluated the effects of the Medtronic MiniMed 770G hybrid closed-loop system on glycemic control and psychological aspects in persons with type 1 diabetes mellitus.

MATERIALS AND METHODS

This 3-month prospective observational study included 22 participants with type 1 diabetes mellitus who used the Medtronic MiniMed 640G predictive low-glucose suspend system and were switched to the 770G system. Time in the range of 70-180 mg/dL and glycated hemoglobin levels were evaluated; satisfaction, emotional distress and quality of life were assessed using self-reported questionnaires, including the Diabetes Treatment Satisfaction Questionnaire Status, Problem Area in Diabetes and Diabetes Therapy-Related Quality of Life.

RESULTS

Time in the range of 70-180 mg/dL increased (63.5 ± 13.4 to 73.0 ± 10.9% [mean ± standard deviation], P = 0.0010), and time above the range of 181-250 mg/dL decreased (26.9 ± 8.9 to 19.6 ± 7.1%, P < 0.0005). Glycated hemoglobin levels decreased (7.7 ± 1.0 to 7.2 ± 0.8%, P = 0.0021). The percentage of participants with time below the range of 54-69 mg/dL <4% of readings increased from 91% to 100% (P < 0.0005). No significant changes were detected in the satisfaction, emotional distress and quality of life levels, but increased sensor calibration might be related to worsened emotional distress and quality of life.

CONCLUSIONS

The hybrid closed-loop system decreased hyperglycemia and minimized hypoglycemia, but did not improve psychological aspects compared with the predictive low-glucose suspend system, probably because sensor calibration was increased.

Sleep duration and food intake in people with type 2 diabetes mellitus and factors affecting confectionery intake

AIMS/INTRODUCTION

We carried out a cross-sectional study of people with type 2 diabetes mellitus to elucidate the association between sleep duration and food intake.

MATERIALS AND METHODS

Overall, 2,887 participants with type 2 diabetes mellitus (mean age 63.0 years; 61.1% men; mean glycated hemoglobin level 7.5%) were included in this study. The participants' self-reported dietary habits and sleep duration were evaluated using a brief self-administered dietary history questionnaire and Pittsburgh Sleep Quality Index, respectively. The participants were categorized into the following four groups based on sleep duration: <6, 6-6.9, 7-7.9 (reference) and ≥8 h.

RESULTS

No significant differences were observed between the groups regarding energy intake (kcal/day), absolute intake (g/day) or relative intake (% energy) of carbohydrates, total fat, proteins and fibers. However, confectionery intake was higher in the <6 h group and lower in the ≥8 h group than in the reference group after adjustment for confounding factors. In multivariate analysis, sleep durations <6 h and ≥8 h significantly correlated with increased (95% confidence interval 0.55 to 3.6; P = 0.0078) and decreased (95% confidence interval -4.0 to -0.32; P = 0.021) confectionery intake, respectively. Confectionery intake was positively correlated with female sex, glycated hemoglobin level and dyslipidemia, whereas it was negatively correlated with alcohol consumption and current smoking status.

CONCLUSIONS

Short sleep duration is associated with high confectionery intake in people with type 2 diabetes mellitus; this might disturb their glycemic control. Therefore, short sleepers with type 2 diabetes mellitus could improve their glycemic control by avoiding confectionery intake and maintaining adequate sleep duration.

The METRO study: a retrospective analysis of the efficacy of metformin for type 2 diabetes in Japan

Metformin monotherapy as first-line treatment for patients with type 2 diabetes (T2D) has been shown to effectively improve blood glucose levels and motivation to undergo treatment and prevent complications. However, no studies have reported its effect when combined with other drugs or compared the effect based on administration time. This study aimed to investigate the effect of metformin administration in Japanese patients with T2D, examine how the introduction line impacts the effect of metformin, and examine the characteristics of patients demonstrating improved blood glucose levels. Data on characteristics of patients who were newly prescribed metformin with no shifting of hypoglycemic agents in the subsequent 24-week observation period, and their age [mean, 56.8 years], body mass index [mean, 27.5 kg/m²], glycated hemoglobin [HbA1c] [mean, 8.1%], and duration of diabetes [mean, 3.0 years] were obtained from the medical records of 201 patients. The changes in HbA1c by introduction line after 24 weeks were -1.59%, -0.91%, -0.89%, and -0.65% in the first, second, third, and fourth induction lines, respectively; earlier introduction more significantly improved blood glucose. The factors significantly associated with HbA1c changes were early introduction, high baseline HbA1c, high estimated glomerular filtration rate, decreased insulin secretion, short estimated duration of diabetes, and increased metformin dose. Furthermore, factors contributing to the largest HbA1c improvement by metformin were high baseline HbA1c and early administration. Metformin is expected to lower blood glucose levels in Japanese patients with T2D, even in those with decreased insulin secretion, due to its early introduction as a first-line drug.

Association of continuous positive airway pressure therapy on cardiac hypertrophy in patients with sleep apnea comorbid with type 2 diabetes mellitus

Previous reports indicated the therapeutic effect of chronic continuous positive airway pressure (CPAP) therapy on cardiac hypertrophy due to sleep apnea syndrome. However, little is known for cases involving diabetic complications. This retrospective observational study examined the effects of CPAP therapy on left ventricular hypertrophy (LVH) in patients with obstructive sleep apnea syndrome (OSAS) and type 2 diabetes mellitus (T2DM). For all cases, the observation period was 3 years from the time when the patient was introduced to CPAP therapy. Overall, 123 patients were divided into a good CPAP group (CPAP ≥4 h/day, n = 63) and non-adherence group (CPAP <4 h/day, n = 60). The mean CPAP usage times were 5.58 ± 1.23 and 1.03 ± 1.17 h/day in the good CPAP and non-adherence groups, respectively. Regression tendencies of the thickness of the left ventricular posterior (-0.30 ± 1.19 mm) and interventricular septal walls (-0.48 ± 1.22 mm) were observed in the good CPAP group. Hypertrophic tendencies of the left ventricular posterior wall (+0.59 ± 1.44 mm) and interventricular septal wall thickness (+0.59 ± 1.43) were observed in the non-adherence group. Left ventricular posterior wall thickness (coefficient: -0.254, p = 0.0376) and interventricular septal wall thickness (coefficient: -0.426, p = 0.0006) were more likely to be greater in the non-adherence group than in the good CPAP group. Patients in the non-adherence group with an apnea hypopnea index ≥30 had increased left ventricular posterior wall thickness (coefficient: -0.263, p = 0.0673) and interventricular septal wall thickness (coefficient: -0.450, p = 0.0011). In conclusion, appropriate CPAP therapy is an effective treatment for LVH in patients with T2DM and OSAS, especially for severe cases.

Comparing the course and delivery outcomes of Japanese twin pregnancies with and without gestational diabetes mellitus: a single-center retrospective analysis

Singleton pregnant women with gestational diabetes mellitus (GDM) are at an increased risk of adverse maternal and neonatal outcomes. Multiple pregnancies are associated with increased risks of perinatal complications; however, the impact of GDM on maternal and neonatal outcomes in multiple pregnancies is unknown, and there are currently few reports on GDM status in twin pregnancies. This study aimed to compare the background and perinatal outcomes between Japanese twin pregnancies with and without GDM at a perinatal center in Japan. Additionally, the clinical course of GDM was investigated. In this retrospective cohort study, women with twin pregnancies underwent GDM screening at Yokohama City University Medical Center from January 2011 to December 2016. Overall, 307 twin pregnancies were divided into GDM (47 cases, 15.3%) and non-GDM (260 cases, 84.7%) groups. GDM-associated pregnancy complications, GDM status, and pregnancy outcomes were ascertained. Women with GDM were older and had a higher pre-pregnancy body mass index than those without GDM. Glycemic control was good in all patients, and there was no difference in delivery outcomes between the two groups. Gestational weight gain was lower in pregnant women with GDM (+8.0 kg) than in those without GDM (+11.8 kg), suggesting the impact of strict nutritional guidance on twin pregnancies with GDM. In conclusion, twin pregnancies with GDM did not have different delivery outcomes compared to those without GDM. To manage twin pregnancies with GDM, this study suggests that it is important to monitor patients' weight and blood glucose levels.

Autosomal dominant diabetes associated with a novel ZYG11A mutation resulting in cell cycle arrest in beta-cells

Diabetes is a genetically heterogeneous disease, for which we are aiming to identify causative genes. Here, we report a missense mutation (c.T1424C:p.L475P) in ZYG11A identified by exome sequencing as segregating with hyperglycemia in a Thai family with autosomal dominant diabetes. ZYG11A functions as a target recruitment subunit of an E3 ubiquitin ligase complex that plays an important role in the regulation of cell cycle. We demonstrate an increase in cells arrested at G₂/mitotic phase among beta-cells deficient for ZYG11A or overexpressing L475P-ZYG11A, which is associated with a decreased growth rate. This is the first evidence linking a ZYG11A mutation to hyperglycemia, and suggesting ZYG11A as a cell cycle regulator required for beta-cell growth. Since most family members were either overweight or obese, but only mutation carriers developed hyperglycemia, our data also suggests the ZYG11A mutation as a genetic factor predisposing obese individuals to beta-cell failure in maintenance of glucose homeostasis.

Parental metabolic syndrome epigenetically reprograms offspring hepatic lipid metabolism in mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Although gene-environment interactions have been implicated in the etiology of several disorders, the impact of paternal and/or maternal metabolic syndrome on the clinical phenotypes of offspring and the underlying genetic and epigenetic contributors of NAFLD have not been fully explored. To this end, we used the liver-specific insulin receptor knockout (LIRKO) mouse, a unique nondietary model manifesting 3 hallmarks that confer high risk for the development of NAFLD: hyperglycemia, insulin resistance, and dyslipidemia. We report that parental metabolic syndrome epigenetically reprograms members of the TGF-β family, including neuronal regeneration-related protein (NREP) and growth differentiation factor 15 (GDF15). NREP and GDF15 modulate the expression of several genes involved in the regulation of hepatic lipid metabolism. In particular, NREP downregulation increases the protein abundance of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and ATP-citrate lyase (ACLY) in a TGF-β receptor/PI3K/protein kinase B-dependent manner, to regulate hepatic acetyl-CoA and cholesterol synthesis. Reduced hepatic expression of NREP in patients with NAFLD and substantial correlations between low serum NREP levels and the presence of steatosis and nonalcoholic steatohepatitis highlight the clinical translational relevance of our findings in the context of recent preclinical trials implicating ACLY in NAFLD progression.

Improved home BP profile with dapagliflozin is associated with amelioration of albuminuria in Japanese patients with diabetic nephropathy: the Yokohama add-on inhibitory efficacy of dapagliflozin on albuminuria in Japanese patients with type 2 diabetes study (Y-AIDA study)

Background

The Y-AIDA study was designed to investigate the renal- and home blood pressure (BP)-modulating effects of add-on dapagliflozin treatment in Japanese individuals with type 2 diabetes mellitus (T2DM) and albuminuria.

Methods

We conducted a prospective, multicenter, single-arm study. Eighty-six patients with T2DM, HbA1c 7.0–10.0%, estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m², and urine albumin-to-creatinine ratio (UACR) ≥ 30 mg/g creatinine (gCr) were enrolled, and 85 of these patients were administered add-on dapagliflozin for 24 weeks. The primary and key secondary endpoints were change from baseline in the natural logarithm of UACR over 24 weeks and change in home BP profile at week 24.

Results

Baseline median UACR was 181.5 mg/gCr (interquartile range 47.85, 638.0). Baseline morning, evening, and nocturnal home systolic/diastolic BP was 137.6/82.7 mmHg, 136.1/79.3 mmHg, and 125.4/74.1 mmHg, respectively. After 24 weeks, the logarithm of UACR decreased by 0.37 ± 0.73 (P < 0.001). In addition, changes in morning, evening, and nocturnal home BP from baseline were as follows: morning systolic/diastolic BP − 8.32 ± 11.42/− 4.18 ± 5.91 mmHg (both P < 0.001), evening systolic/diastolic BP − 9.57 ± 12.08/− 4.48 ± 6.45 mmHg (both P < 0.001), and nocturnal systolic/diastolic BP − 2.38 ± 7.82/− 1.17 ± 5.39 mmHg (P = 0.0079 for systolic BP, P = 0.0415 for diastolic BP). Furthermore, the reduction in UACR after 24 weeks significantly correlated with an improvement in home BP profile, but not with changes in other variables, including office BP. Multivariate linear regression analysis also revealed that the change in morning home systolic BP was a significant contributor to the change in log-UACR.

Conclusions

In Japanese patients with T2DM and diabetic nephropathy, dapagliflozin significantly improved albuminuria levels and the home BP profile. Improved morning home systolic BP was associated with albuminuria reduction.

Trial registration The study is registered at the UMIN Clinical Trials Registry (UMIN000018930; http://www.umin.ac.jp/ctr/index-j.htm). The study was conducted from July 1, 2015 to August 1, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0912-3) contains supplementary material, which is available to authorized users.

Signaling between pancreatic β cells and macrophages via S100 calcium-binding protein A8 exacerbates β-cell apoptosis and islet inflammation

Chronic low-grade inflammation in the pancreatic islets is observed in individuals with type 2 diabetes, and macrophage levels are elevated in the islets of these individuals. However, the molecular mechanisms underlying the interactions between the pancreatic β cells and macrophages and their involvement in inflammation are not fully understood. Here, we investigated the role of S100 calcium-binding protein A8 (S100A8), a member of the damage-associated molecular pattern molecules (DAMPs), in β-cell inflammation. Co-cultivation of pancreatic islets with unstimulated peritoneal macrophages in the presence of palmitate (to induce lipotoxicity) and high glucose (to induce glucotoxicity) synergistically increased the expression and release of islet-produced S100A8 in a Toll-like receptor 4 (TLR4)-independent manner. Consistently, a significant increase in the expression of the S100a8 gene was observed in the islets of diabetic db/db mice. Furthermore, the islet-derived S100A8 induced TLR4-mediated inflammatory cytokine production by migrating macrophages. When human islet cells were co-cultured with U937 human monocyte cells, the palmitate treatment up-regulated S100A8 expression. This S100A8-mediated interaction between islets and macrophages evoked β-cell apoptosis, which was ameliorated by TLR4 inhibition in the macrophages or S100A8 neutralization in the pancreatic islets. Of note, both glucotoxicity and lipotoxicity triggered S100A8 secretion from the pancreatic islets, which in turn promoted macrophage infiltration of the islets. Taken together, a positive feedback loop between islet-derived S100A8 and macrophages drives β-cell apoptosis and pancreatic islet inflammation. We conclude that developing therapeutic approaches to inhibit S100A8 may serve to prevent β-cell loss in patients with diabetes.

Lipid-lowering agents inhibit hepatic steatosis in a non-alcoholic steatohepatitis-derived hepatocellular carcinoma mouse model

Non-alcoholic fatty liver disease (NAFLD) is associated with various metabolic disorders, and the therapeutic strategies for treating NAFLD and non-alcoholic steatohepatitis (NASH) have not been fully established. In the present study, we examined whether lipid-lowering agents inhibited the progression of NAFLD and tumorigenesis in a non-alcoholic steatohepatitis-derived hepatocellular carcinoma model mouse (STAM mice) generated by streptozotocin injection and a high-fat diet. Seven-week-old STAM mice were divided into groups fed a high-fat diet (Ctl) or a high-fat diet supplemented with ezetimibe (Ez), fenofibrate (Ff), rosuvastatin (Rs), ezetimibe plus fenofibrate (EF), or ezetimibe plus rosuvastatin (ER) for 4 weeks. At the end of the experiments, an oral glucose tolerance test, an insulin tolerance test, biochemical analyses using serum and liver, and a histological analysis of liver were performed in 11-week-old STAM mice. The lipid-lowering agents did not affect the body weight or the casual blood glucose levels in any of the groups. The serum triglyceride level was significantly decreased by Ff, Rs, and EF. Glucose tolerance was improved by Ez and Ff, but none of these agents improved insulin sensitivity. A histochemical analysis revealed that the lipid-lowering agents, with the exception of Rs, significantly inhibited the progression of hepatic steatosis. Nonetheless, no significant changes in the incidence of hepatic tumors were observed in any of the groups. Lipid-lowering agents inhibited the progression of hepatic steatosis without suppressing tumorigenesis in STAM mice. Our data has implications for the mechanism underlying steatosis-independent hepatic tumorigenesis in mice.

β-Cell proliferation after a partial pancreatectomy is independent of IRS-2 in mice

The glucokinase-induced up-regulation of insulin receptor substrate 2 (IRS-2) plays an important role in β-cell adaptive proliferation in response to high-fat diet-induced insulin resistance. This study aimed to investigate the role of IRS-2 in the proliferation of β-cells after a 60% partial pancreatectomy. IRS-2-deficient (IRS-2(-/-)) mice or wild-type mice were subjected to a pancreatectomy (60% partial pancreatectomy) or a sham operation (Sham). The β-cell proliferation and gene expression profiles of the islets were then assessed. Gene expression in islets from pancreatectomized and Sham C57BL/6J male mice was analyzed using a cDNA microarray analysis. To compare with β-cell proliferation induced by a high-fat diet, Gck(+/-) mice subjected to a pancreatectomy were also analyzed. The IRS-2(-/-) mice exhibited β-cell expansion and a significant increase in β-cell proliferation after the pancreatectomy, compared with the Sham group. Although glucose-stimulated insulin secretion from islets was not impaired, IRS-2(-/-) mice manifested severe hyperglycemia after the pancreatectomy. The expression levels of Aurora kinase B, Cyclin A, and Cyclin B1 in the pancreatectomized islets were also enhanced in the IRS-2(-/-) mice. A gene set enrichment analysis suggested an association between the genes that were up-regulated in the pancreatectomized islets and those involved in M phase progression in the cell cycle. β-Cell proliferation after a pancreatectomy was observed even in the Gck(+/-) mice. In conclusion, IRS-2 was not required for β-cell proliferation but might be needed for functional β-cell mass, after a pancreatectomy. A partial pancreatectomy in mice may be an attractive model for the development of new strategy for exploring the unique nature of β-cell proliferation.

Metformin prevents liver tumorigenesis induced by high-fat diet in C57Bl/6 mice

The prevalence of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is increasing with the growing epidemics of obesity and diabetes. NAFLD encompasses a clinicopathologic spectrum of disease ranging from isolated hepatic steatosis to NASH, which is a more aggressive form of fatty liver disease, to cirrhosis and, finally, hepatocellular carcinoma (HCC). The exact mechanism behind the development of HCC in NASH remains unclear; however, it has been established that hepatic steatosis is the important risk factor in the development of HCC. Metformin has recently drawn attention because of its potential antitumor effect. Here, we investigated the effects of metformin on high-fat diet (HFD)-induced liver tumorigenesis, using a mouse model of NASH and liver tumor. Metformin prevented long-term HFD-induced liver tumorigenesis in C57Bl/6 mice. Of note, metformin failed to protect against liver tumorigenesis in mice that had already begun to develop NAFLD. Metformin improved short-term HFD-induced fat accumulation in the liver, associated with the suppression of adipose tissue inflammation. Collectively, these results suggest that metformin may prevent liver tumorigenesis via suppression of liver fat accumulation in the early stage, before the onset of NAFLD, which seems to be associated with a delay in the development of inflammation of the adipose tissue.

Glucokinase activation ameliorates ER stress-induced apoptosis in pancreatic β-cells

The derangement of endoplasmic reticulum (ER) homeostasis triggers β-cell apoptosis, leading to diabetes. Glucokinase upregulates insulin receptor substrate 2 (IRS-2) expression in β-cells, but the role of glucokinase and IRS-2 in ER stress has been unclear. In this study, we investigated the impact of glucokinase activation by glucokinase activator (GKA) on ER stress in β-cells. GKA administration improved β-cell apoptosis in Akita mice, a model of ER stress-mediated diabetes. GKA increased the expression of IRS-2 in β-cells, even under ER stress. Both glucokinase-deficient Akita mice and IRS-2-deficient Akita mice exhibited an increase in β-cell apoptosis, compared with Akita mice. β-cell-specific IRS-2-overexpressing (βIRS-2-Tg) Akita mice showed less β-cell apoptosis than Akita mice. IRS-2-deficient islets were vulnerable, but βIRS-2-Tg islets were resistant to ER stress-induced apoptosis. Meanwhile, GKA regulated the expressions of C/EBP homologous protein (CHOP) and other ER stress-related genes in an IRS-2-independent fashion in islets. GKA suppressed the expressions of CHOP and Bcl2-associated X protein (Bax) and protected against β-cell apoptosis under ER stress in an ERK1/2-dependent, IRS-2-independent manner. Taken together, GKA ameliorated ER stress-mediated apoptosis by harmonizing IRS-2 upregulation and the IRS-2-independent control of apoptosis in β-cells.

Trefoil factor 2 promotes cell proliferation in pancreatic β-cells through CXCR-4-mediated ERK1/2 phosphorylation

Decreased β-cell mass is a hallmark of type 2 diabetes, and therapeutic approaches to increase the pancreatic β-cell mass have been expected. In recent years, gastrointestinal incretin peptides have been shown to exert a cell-proliferative effect in pancreatic β-cells. Trefoil factor 2 (TFF2), which is predominantly expressed in the surface epithelium of the stomach, plays a role in antiapoptosis, migration, and proliferation. The TFF family is expressed in pancreatic β-cells, whereas the role of TFF2 in pancreatic β-cells has been obscure. In this study, we investigated the mechanism by which TFF2 enhances pancreatic β-cell proliferation. The effects of TFF2 on cell proliferation were evaluated in INS-1 cells, MIN6 cells, and mouse islets using an adenovirus vector containing TFF2 or a recombinant TFF2 peptide. The forced expression of TFF2 led to an increase in bromodeoxyuridine (BrdU) incorporation in both INS-1 cells and islets, without any alteration in insulin secretion. TFF2 significantly increased the mRNA expression of cyclin A2, D1, D2, D3, and E1 in islets. TFF2 peptide increased ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. A MAPK kinase inhibitor (U0126) abrogated the TFF2 peptide-mediated proliferation of MIN6 cells. A CX-chemokine receptor-4 antagonist also prevented the TFF2 peptide-mediated increase in ERK1/2 phosphorylation and BrdU incorporation in MIN6 cells. These results indicated that TFF2 is involved in β-cell proliferation at least partially via CX-chemokine receptor-4-mediated ERK1/2 phosphorylation, suggesting TFF2 may be a novel target for inducing β-cell proliferation.

Double-blind randomized clinical trial of the effects of ezetimibe on postprandial hyperlipidaemia and hyperglycaemia

AIM

Ezetimibe selectively blocks intestinal cholesterol absorption by inhibiting Niemann-Pick C1-like 1 (NPC1L1) and reducing LDL cholesterol (LDL-C). In animals, ezetimibe reversed diet-induced obesity, liver steatosis, and insulin resistance. In humans, its potential effects on liver steatosis and insulin resistance have been suggested. We investigated the effects of ezetimibe on postprandial hyperlipidaemia and hyperglycaemia in obese subjects with dyslipidaemia in a double-blind randomized crossover trial.

METHODS

Twenty obese men with hypertriglyceridaemia were assigned randomly to an ezetimibe- or a placebo-precedence-treated group. Subjects in the ezetimibe group were treated with ezetimibe (10 mg/day) for the first 4 weeks, followed by a 4-week interval and then treated with placebo for another 4 weeks. The placebo group received these treatments in reverse order. Subjects were requested to fast for at least 12 hours and then received a standard meal. Blood samples were collected at 0, 30, 60, 120, 240, 360 and 480 minutes after the meal on Days 0, 28, 56 and 84 and were used to measure the lipid and glucose metabolism markers.

RESULTS

Ezetimibe significantly decreased the postprandial serum triglyceride excursion (p=0.01) and fasting serum LDL-C, remnant-like particles(RLP) and ApoB48 levels (p<0.05). Postprandial glucose excursion, serum insulin levels, serum glucose-dependent insulinotropic polypeptide (GIP) and active glucagon-like peptide-1 (GLP-1) were not significantly affected by ezetimibe treatment.

CONCLUSION

Ezetimibe restored the postprandial dysregulation of lipid but did not affect glucose metabolism in a double-blind randomized crossover trial.

Plasminogen activator inhibitor-1 is associated with renal dysfunction independent of BMI and serum lipid levels in patients with type 2 diabetes

We investigated a possible association between serum plasminogen activator inhibitor-1 (PAI-1) levels and renal dysfunction in 124 type 2 diabetes patients. Multiple linear regression analyses indicated that the PAI-1 levels were significantly inversely correlated with estimated glomerular filtration rate (eGFR) independent of albuminuria, BMI, LDL-C, and triglyceride.

Effects of liraglutide on β-cell-specific glucokinase-deficient neonatal mice

The glucagon-like peptide-1 receptor agonist liraglutide is used to treat diabetes. A hallmark of liraglutide is the glucose-dependent facilitation of insulin secretion from pancreatic β-cells. In β-cells, the glycolytic enzyme glucokinase plays a pivotal role as a glucose sensor. However, the role of glucokinase in the glucose-dependent action of liraglutide remains unknown. We first examined the effects of liraglutide on glucokinase haploinsufficient (Gck(+/-)) mice. Single administration of liraglutide significantly improved glucose tolerance in Gck(+/-) mice without increase of insulin secretion. We also assessed the effects of liraglutide on the survival rates, metabolic parameters, and histology of liver or pancreas of β-cell-specific glucokinase-deficient (Gck(-/-)) newborn mice. Liraglutide reduced the blood glucose levels in Gck(-/-) neonates but failed to prolong survival, and all the mice died within 1 wk. Furthermore, liraglutide did not improve glucose-induced insulin secretion in isolated islets from Gck(-/-) neonates. Liraglutide initially prevented increases in alanine aminotransferase, free fatty acids, and triglycerides in Gck(-/-) neonates but not at 4 d after birth. Liraglutide transiently prevented liver steatosis, with reduced triglyceride contents and elevated glycogen contents in Gck(-/-) neonate livers at 2 d after birth. Liraglutide also protected against reductions in β-cells in Gck(-/-) neonates at 4 d after birth. Taken together, β-cell glucokinase appears to be essential for liraglutide-mediated insulin secretion, but liraglutide may improve glycemic control, steatosis, and β-cell death in a glucokinase-independent fashion.

Control of beta cell function and proliferation in mice stimulated by small-molecule glucokinase activator under various conditions

AIMS/HYPOTHESIS

We investigated changes in the expression of genes involved in beta cell function and proliferation in mouse islets stimulated with glucokinase activator (GKA) in order to elucidate the mechanisms by which GKA stimulates beta cell function and proliferation.

METHODS

Islets isolated from mice were used to investigate changes in the expression of genes related to beta cell function and proliferation stimulated by GKA. In addition, Irs2 knockout (Irs2 (-/-)) mice on a high-fat diet or a high-fat diet containing GKA were used to investigate the effects of GKA on beta cell proliferation in vivo.

RESULTS

In wild-type mice, Irs2 and Pdx1 expression was increased by GKA. In Irs2 (-/-) mice, GKA administration increased the glucose-stimulated secretion of insulin and Pdx1 expression, but not beta cell proliferation. It was particularly noteworthy that oxidative stress inhibited the upregulation of the Irs2 and Pdx1 genes induced by GKA. Moreover, whereas neither GKA alone nor exendin-4 alone upregulated the expression of Irs2 and Pdx1 in the islets of db/db mice, prior administration of exendin-4 to the mice caused GKA to increase the expression of these genes.

CONCLUSIONS/INTERPRETATION

GKA-stimulated IRS2 production affected beta cell proliferation but not beta cell function. Oxidative stress diminished the effects of GKA on the changes in expression of genes involved in beta cell function and proliferation. A combination of GKA and an incretin-related agent might therefore be effective in therapy.

Impact of the dipeptidyl peptidase-4 inhibitor vildagliptin on glucose tolerance and β-cell function and mass in insulin receptor substrate-2-knockout mice fed a high-fat diet

Type 2 diabetes is characterized by diminished pancreatic β-cell mass and function. Glucagon-like peptide-1 has been reported to increase islet cell proliferation and reduce apoptosis of β-cells in rodents. In this study, we explored the effect of chronic administration of the dipeptidyl peptidase-4 inhibitor vildagliptin on glucose tolerance, β-cell function, and β-cell mass in Irs2-knockout (Irs2(-/-)) mice. Wild-type and Irs2(-/-) mice were fed a high-fat diet for 20 wk, with or without vildagliptin. In both genotypes of mice, vildagliptin significantly decreased the area under the curve (0-120 min) of blood glucose and increased the insulin response to glucose during the oral glucose tolerance test. In the oral glucose tolerance test performed 1 d after discontinuation of vildagliptin administration, the area under the curve (0-120 min) of blood glucose was still significantly decreased and the insulin response to glucose was significantly increased in the Irs2(-/-) mice treated with vildagliptin as compared with the values in the mice not treated with vildagliptin. Histochemical analysis of the pancreatic islets revealed significant increase of the β-cell mass and decrease in the proportion of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive β-cells but no significant increase of the bromodeoxyuridine incorporation in Irs2(-/-) mice treated with vildagliptin. Our results suggest that vildagliptin improved glucose tolerance and increased the β-cell mass by reducing β-cell apoptosis in the Irs2(-/-) mice, and that the reduction of β-cell apoptosis by vildagliptin was independent of the Irs2 expression in the cells.

Protective effects of dipeptidyl peptidase-4 (DPP-4) inhibitor against increased β cell apoptosis induced by dietary sucrose and linoleic acid in mice with diabetes

Chronic exposure to high glucose and fatty acid levels caused by dietary sugar and fat intake induces β cell apoptosis, leading to the exacerbation of type 2 diabetes. Oleic acid and linoleic acid are two major dietary fatty acids, but their effects in diabetes are unclear. We challenged β cell-specific glucokinase haploinsufficient (Gck(+/-)) mice with a diet containing sucrose and oleic acid (SO) or sucrose and linoleic acid (SL) and analyzed β cell apoptosis. In Gck(+/-) but not wild-type mice, SL significantly decreased the β cell mass and β cell proportion in islet cells arising from increased apoptosis to a greater degree than did SO. The mRNA expression of SREBP-1c was significantly higher, and that of E-cadherin was significantly lower in the islets of Gck(+/-) mice fed SL compared with mice fed SO. We next evaluated monotherapy with desfluorositagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, in these mouse groups. DPP-4 inhibitor protected against β cell apoptosis, restored the β cell mass, and normalized islet morphology in Gck(+/-) mice fed SL. DPP-4 inhibition normalized the changes in the islet expression of SREBP-1c and E-cadherin mRNA induced by the SL diet. Furthermore, linoleic acid induced β cell apoptosis to a greater degree in the presence of high glucose levels than in the presence of low glucose levels in vitro in islets and MIN6 cells, whereas a GLP-1 receptor agonist prevented apoptosis. In conclusion, SL exacerbated β cell apoptosis in diabetic Gck(+/-) mice but not in euglycemic wild-type mice, and DPP-4 inhibition protected against these effects.

Effects of pre-meal versus post-meal administration of miglitol on plasma glucagon-like peptide-1 and glucosedependent insulinotropic polypeptide levels in healthy men

We previously reported that the administration of miglitol after a meal was equally effective as administration before a meal. Since glucagon-like peptide-1 (GLP-1) reportedly promotes islet cell growth and inhibits apoptosis in animal models, an increase in GLP-1 secretion might also be beneficial for islet cell function and mass in humans. Miglitol reportedly enhances GLP-1 responses and reduces glucose-dependent insulinotropic polypeptide (GIP). However, whether the effect of miglitol on these incretins is comparable when miglitol is administered before or after a meal remains uncertain. Here, we compared the effects of the pre-meal versus post-meal administration of miglitol on the plasma active GLP-1 and total GIP levels in healthy men. Miglitol was administered according to three different intake schedules in each subject (control: no drug, intake 1: drug administered just before a meal [50 mg]; intake 2: drug administered at 30 min after the start of a meal [50 mg]). The area under the curve (AUC) of the plasma GLP-1 level for the intake 1 group was significantly greater than those of the control and intake 2 groups. The AUCs of the plasma GIP level for the intake 1 and 2 groups were significantly smaller than that of the control. The administration of miglitol just before a meal, rather than after a meal, is recommended in view of the up-regulation of GLP-1.