Kazuaki Shinoda

Ezetimibe decreases SREBP-1c expression in liver and reverses hepatic insulin resistance in mice fed a high-fat diet

Ezetimibe inhibits intestinal cholesterol absorption, thereby reducing serum cholesterol. Recent studies suggest that ezetimibe affects liver steatosis and insulin resistance. We investigated the impact of ezetimibe on insulin sensitivity and glucose metabolism in C57BL/6 mice. We analyzed 4 mouse groups fed the following diets: normal chow (4% fat) for 12 weeks, normal chow for 10 weeks followed by normal chow plus ezetimibe for 2 weeks, high-fat chow (32% fat) for 12 weeks, and high-fat chow for 10 weeks followed by high-fat chow plus ezetimibe for 2 weeks. In the normal chow + ezetimibe group, ezetimibe had no impact on body weight, fat mass, lipid metabolism, liver steatosis, glucose tolerance, or insulin sensitivity. In the high-fat chow + ezetimibe group, ezetimibe had no impact on body weight or fat mass but significantly decreased serum low-density lipoprotein cholesterol, triglyceride, and glutamate pyruvate transaminase levels; liver weight; hepatic triglyceride content; and hepatic cholesterol content and increased the hepatic total bile acid content. In association with increases in IRS-2 and Akt phosphorylation, ezetimibe ameliorated hepatic insulin resistance in the high-fat chow + ezetimibe group, but had no effect on insulin sensitivity in primary cultured hepatocytes. A DNA microarray and Taqman polymerase chain reaction revealed that ezetimibe up-regulated hepatic SREBP2 and SHP expression and down-regulated hepatic SREBP-1c expression. SHP silencing mainly in the liver worsened insulin resistance, and ezetimibe protected against insulin resistance induced by down-regulation of SHP. Ezetimibe down-regulated SREBP-1c in the liver and reversed hepatic insulin resistance in mice fed a high-fat diet.

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.

Comparison of pre- vs. postmeal administration of miglitol for 3 months in type 2 diabetic patients

Aim:  α‐Glucosidase inhibitors (αGIs) primarily modify postprandial plasma glucose levels and should be taken just before meals. We previously demonstrated that a single administration of miglitol within 30 min after the start of a meal was equally effective as when administered just before a meal. We here compared pre‐ vs. postmeal administration of miglitol for 3 months in type 2 diabetic patients.

Glycemic control after addition of the dipeptidyl peptidase-4 inhibitor alogliptin in patients with type 2 diabetes showing inadequate response to thrice-a-day treatment with α-glucosidase inhibitors.

Objective: We investigated the effect of addition of alogliptin, while continuing the α-glucosidase inhibitor (αGI) administration at the same or reduced dose, or discontinuing the drug, on the glycemic control in type 2 diabetic patients showing inadequate response to αGI treatment. Research design and methods: A prospective, randomized, controlled, multicenter interventional study trial. Subjects were randomly assigned to treatment with alogliptin alone (Intake 0 group), or alogliptin in addition to an αGI administered once-/twice-/thrice-daily (Intake 1, 2 and 3 groups). Main outcome measures: Changes in glycemic control were measured. Results: The HbA1c and glycoalbumin levels at 1 and 3 months were significantly lower than the values at the baseline in the Intake 1, 2 and 3 groups, but not the Intake 0 group. The body weight at 3 months was significantly lower than that at the baseline in the Intake 3 group. There were no significant differences in the degree of satisfaction or participating volition recorded, before and after the start of the study treatments. Conclusions: Addition of alogliptin to once-/twice-daily administration of an αGI may be effective for obtaining improved glycemic control, without lowering the treatment satisfaction level, in type 2 diabetic patients.

Self-Injection of Insulin Using Appropriate Supportive Devices in Handicapped Subjects with Diabetes

BACKGROUND To self-inject insulin, individuals with diabetes must be able to attach the needle to the injector, recognize the appropriate insulin dosage, detach the needle from the injector, and perform a series of operations necessary for the actual injection. These tasks require a grip strength that is strong enough to hold the necessary devices, eyesight, the use of both hands, and at least a minimum intellectual capacity. Subjects who are unable to grasp or handle the devices required for insulin injection often have difficulties with the self-injection of insulin. METHODS We treated four diabetes patients who had trouble grasping objects and using both hands. One patient had lost five fingers in an accident, two patients had suffered from ischemic cerebral infarction resulting in complete one-sided hemiplegia with no movement in one arm, and one patient had limited muscular power in an arm as a result of spinal cord disease. The plasma glucose control was poor, and the initiation of insulin therapy was necessary in each of these patients. In three cases, we used a commercially available self-injection device (HumaHelper; Eli Lilly Japan K.K., Kobe, Japan) to enable self-injection; in the fourth case, we used a newly manufactured device similar to HumaHelper. RESULTS All the patients were able to inject insulin by themselves using the appropriate supplementary devices. The blood glucose control of all the patients subsequently improved. CONCLUSION Existing or newly manufactured supportive devices can enable handicapped subjects to self-inject insulin.

Effect of Switching from Sulphonylurea to Repaglinide Twice or Three Times Daily for 4 Months on Glycemic Control in Japanese Patients with Type 2 Diabetes.

Objective Switching from sulfonylureas to repaglinide in patients with type 2 diabetes improves glycemic control; however, the optimal dosage has not been fully evaluated. We designed to show that repaglinide was equivalent to sulfonylurea in Japanese patients with type 2 diabetes. We herein evaluated whether we could switch from sulfonylureas to repaglinide twice or thrice daily in Japanese adult patients who had been treated with anti-diabetic drugs, including sulfonylureas, and whose conditions were moderately well-controlled. Methods A total of 78 patients taking less than half the Japanese maximum dose of sulfonylurea were randomized into three groups: 26 in group A (switching from sulfonylureas to taking 0.25 or 0.5 mg of repaglinide just before breakfast and dinner twice daily), 27 in group B (switching from sulfonylureas to taking 0.25 or 0.5 mg of repaglinide just before meals thrice daily), and 25 in group C (continuing to take sulfonylurea). Blood samples were collected at 0, 1, 2, 3, and 4 months following the initiation of the maintenance period. Results The HbA1c and glycoalbumin levels did not significantly differ among the three groups after 4 months of treatment. Conclusion With the assumption that 1 mg of glimepiride is equivalent to 1.25 mg of glibenclamide or 40 mg of gliclazide, the administration of repaglinide (0.44 mg/meal) twice and thrice daily is similar to the efficacy of sulfonylurea (glimepiride 1.63-1.98 mg/day) after four months of treatment in Japanese patients with moderately well-controlled type 2 diabetes (HbA1c, 7-7.5%).

Effect of repaglinide, administered two or three times daily for 3 months, on glycaemic control in Japanese patients with type 2 diabetes mellitus

Objectives To compare the efficacy, safety and compliance of repaglinide, administered either two or three times daily, regarding glycaemic control in patients with type 2 diabetes mellitus. Methods Japanese adults with type 2 diabetes mellitus, who had been treated without sulphonylureas or glinides for >3 months, were randomly assigned to two groups to receive either 0.25 mg repaglinide, oral, twice daily (group A) or 0.25 mg repaglinide, oral, three times daily (group B). Glycosylated haemoglobin (HbA1c), glycoalbumin (GA) and 1,5-anhydroglucitol (1,5-AG) levels were measured at 0, 1, 2 and 3 months after treatment commenced. Results Out of 43 patients who enrolled (group A, n = 22; group B, n = 21), 33 patients completed the trial (group A, n = 16; group B, n = 17). No significant between-group differences in HbA1c, GA, or 1,5-AG levels were seen at 1–3 months. No severe hypoglycaemic episodes or other adverse events were observed. Conclusions Minimal-dose repaglinide administered twice daily was similar in efficacy and safety to three-times-daily administration, in Japanese patients with type 2 diabetes mellitus. Administration of repaglinide twice daily could be an alternative regimen for patients who cannot take repaglinide three times daily.