Remission of hyperglycemia after withdrawal of oral antidiabetic drugs in Japanese patients with early-stage type 2 diabetes.

AIMS/INTRODUCTION: To assess whether intervention with oral antidiabetic drug in Japanese patients with the early stage of type 2 diabetes could provide a significant remission of the disease process. MATERIALS AND METHODS: Patients with diabetes duration <5 years were randomized to the lifestyle modification (LFS), pioglitazone (PIO) or sulfonylurea (SU) treatment group. In phase 1 as the on-treatment period and in phase 2 as the off-treatment period, the duration that glycated hemoglobin (HbA1c) was maintained at less than the target was compared among groups. RESULTS: A total of 278 patients were assigned to LFS (n = 84), PIO (n = 101) and SU (n = 93), and 212 patients completed phase 1. The number of patients that dropped out because of HbA1c elevation was larger in the LFS group, and the duration of HbA1c being maintained at <7.9% was longer in the SU group than the other groups. The duration of HbA1c being maintained at <7.4% in phase 2 was significantly shorter in the SU group than in the other groups. The proportion of patients who achieved HbA1c <6.9% or 6.2% at the end of phase 1 was obviously less in the LFS group than other groups. The duration of HbA1c being maintained at <6.2% in phase 2 was longer in the PIO group than other groups, although not significant statistically. An increase in serum adiponectin and decreases in high-sensitivity C-reactive protein and homeostatic model assessment of insulin resistance were shown in patients treated with PIO, but not LFS and SU, in phase 1, but were canceled in the drug-off phase 2 period. CONCLUSIONS: PIO treatment provided a prolonged remission of hyperglycemia after stopping the dosage in patients with the early stage of type 2 diabetes.

Seven-year Observational Study on the Association between Glycemic Control and the New Onset of Macroangiopathy in Japanese Subjects with Type 2 Diabetes.

Objective To examine the association between glycemic control and the new onset of macroangiopathy in Japanese subjects with type 2 diabetes. Methods We examined seven-year follow-up data for 572 patients. We divided the subjects by the average of seven-year glycemic control based on the guidelines. First, we excluded the subjects with a past history of macroangiopathy and then examined the incidence of the new onset of macroangiopathy. Results The incidence of ischemic heart disease (IHD) was 1.0% per year, and that of cerebral vascular disease (CVD) was 1.0% per year. However, IHD events were not observed at all for five years in the most intensive glycemic control group (HbA1c<6%). Similarly, CVD events were not observed at all for seven years in the most intensive glycemic control group (HbA1c<6%). In addition, the cumulative incidence rate of IHD tended to increase as the glycemic control became poorer (HbA1c<6%, 4.5%; 6%≤HbA1c<7%, 6.0%; 7%≤HbA1c<8%, 7.2%; HbA1c≥8%, 10.7%). Furthermore, a logistic regression analysis showed that the duration of diabetes and HbA1c level were independent risk factors contributing to the onset of IHD, but not to the onset of CVD. Conclusion This seven-year observational study showed the possible association between glycemic control and the onset of macroangiopathy in a total of 572 Japanese subjects with type 2 diabetes.

Azelnidipine, but not amlodipine, reduces urinary albumin excretion and carotid atherosclerosis in subjects with type 2 diabetes: blood pressure control with olmesartan and azelnidipine in Type 2 diabetes (BOAT2 study).

To evaluate the efficacy of azelnidipine and amlodipine on diabetic nephropathy and atherosclerosis, we designed a prospective and randomized controlled clinical study in type 2 diabetic patients with stable glycemic control with fixed dose of anti-diabetic medication. Although there was no difference in blood pressure between both groups, urinary albumin excretion and maximum carotid intima-media thickness were reduced in azelnidipine group, but not in amlodipine group. In addition, inflammatory cytokine levels were decreased only in azelnidipine group which possibly explains such beneficial effects of azelnidipine on urinary albumin excretion and carotid atherosclerosis.

Anti-hypertensive azelnidipine preserves insulin signaling and glucose uptake against oxidative stress in 3T3-L1 adipocytes.

It is known that reactive oxygen species (ROS) are involved in the development of insulin resistance as well as pancreatic ß-cell dysfunction both of which are often observed in type 2 diabetes. In this study, we evaluated the effects of azelnidipine, a calcium channel blocker, on ROS-mediated insulin resistance in adipocytes. When 3T3-L1 adipocytes were exposed to ROS, insulin-mediated glucose uptake was suppressed, but such phenomena were not observed in the presence of azelnidipine. Phosphorylation of insulin receptor and phosphorylation of Akt were suppressed by ROS, which was mitigated by azelnidipine treatment. Activation of the JNK pathway induced by ROS was also reduced by azelnidipine. Various inflammatory cytokine levels were increased by ROS, which was also suppressed by azelnidipine treatment. In contrast, adiponectin mRNA and secreted adiponectin levels were reduced by ROS, which was refilled by azelnidipine treatment. In conclusion, azelnidipine preserves insulin signaling and glucose uptake against oxidative stress in 3T3-L1 adipocytes.

Combination of DPP-4 inhibitor and PPARγ agonist exerts protective effects on pancreatic ß-cells in diabetic db/db mice through the augmentation of IRS-2 expression.

We investigated the effects of long- and short-term treatment with pioglitazone (Pio) and/or alogliptin (Alo) on ß-cells in diabetic db/db mice. Six-week-old male db/db mice received Pio (25 mg/kg, oral) and/or Alo (30 mg/kg, oral) for 4 weeks and for 2 days. Blood glucose levels were decreased after 4-week intervention, but not after 2-day intervention. Pio increased adiponectin levels, and Alo decreased glucagon levels and increased active GlP-1 levels. Insulin sensitivity was restored by Pio. After 4-week treatment, ß-cell mass was increased (over 2-fold increase) and expression levels of various ß-cell-related factors were restored. Expression levels of IRS-2 and various downstream factors were up-regulated by Pio and Alo after 2-day and 4-week intervention. In addition, mRNA and protein levels of IRS-2 and various downstream factors were up-regulated in MIN6 cells after 24-h exposure to Pio and exendin-4. These results suggest that Pio and Alo additively up-regulate IRS-2 expression independently of the alteration of glycemic control. Taken together, combination of Pio and Alo exerts protective effects on ß-cells in diabetic db/db mice, at least in part, through the augmentation of IRS-2 expression.

Protective effects of pioglitazone and/or liraglutide on pancreatic ß-cells in db/db mice: Comparison of their effects between in an early and advanced stage of diabetes.

The aim was to compare the protective effects of pioglitazone (PIO) and/or liraglutide (LIRA) on ß-cells with the progression of diabetes. Male db/db mice were treated with PIO and/or LIRA for 2 weeks in an early and advanced stage. In an early stage insulin biosynthesis and secretion were markedly increased by PIO and LIRA which was not observed in an advanced stage. In concomitant with such phenomena, expression levels of various ß-cell-related factors were up-regulated by PIO and LIRA only in an early stage. Furthermore, ß-cell mass was also increased by the treatment only in an early stage. Although there was no difference in apoptosis ratio between the two stages, ß-cell proliferation was augmented by the treatment only in an early stage. In conclusion, protective effects of pioglitazone and/or liraglutide on ß-cells were more powerful in an early stage of diabetes compared to an advanced stage.

Dietary restriction preserves the mass and function of pancreatic ß cells via cell kinetic regulation and suppression of oxidative/ER stress in diabetic mice.

To assess the molecular mechanisms by which dietary restriction preserves the ß-cell mass and function in diabetic db/db mice. Male db/db mice were divided into two groups with or without diet restriction. Daily food intake of db/db mice was adjusted to that of the control db/m mice, which was determined in advance. A dietary restriction was implemented for 6 weeks from 6 weeks of age. Islet morphology, ß-cell function and gene expression profiles specific for pancreatic islet cells were compared. Food intake in db/m mice was 50% of that in db/db mice. Impaired glucose tolerance and insulin sensitivity were significantly ameliorated in db/db mice with dietary restriction. The pancreatic ß-cell mass was greater in mice with dietary restriction than that in mice without intervention. The dietary restriction significantly increased cyclin D gene expression and down-regulated CAD gene expression at 12 weeks compared with untreated db/db mice. Antiapoptotic bcl-2 gene expression was significantly increased, whereas genes related to oxidative stress, ER stress and inflammatory processes, such as NADPH oxidase, CHOP10 and TNF, were markedly down-regulated in mice with dietary restriction. Dietary restriction preserved the pancreatic ß-cell function and ß-cell mass in diabetic db/db mice, suggesting that alimentary therapy prevented ß-cell loss by suppressing cellular apoptosis and antioxidative stress in the pancreatic ß cells.

Concomitant use of miglitol and mitiglinide as initial combination therapy in type 2 diabetes mellitus.

AIM: To evaluate the efficacy of miglitol and mitiglinide alone or in combination on the metabolic profile and incretin secretion in Japanese type 2 diabetes patients. METHODS: Patients on diet and exercise with or without metformin, were randomized to receive either miglitol, mitiglinide, or a combination, three times daily for 12 weeks. RESULTS: At 12 weeks, HbA1c decreased significantly (p<0.001) and 1,5-AG increased significantly (p<0.001) in all three groups, with the greatest change seen with combination therapy. Effective improvement of postprandial hyperglycemia was demonstrated by a meal-loading test in all three interventions but serum insulin concentration was not increased by miglitol. In a subset of patients without prior metformin administration, faster and better glycemic control was achieved with the initial combination. After meal loading, serum total GLP-1 significantly increased only with miglitol monotherapy (p<0.05) and serum total GIP significantly decreased (p<0.01) in the arms employing miglitol after 12 weeks. CONCLUSION: Miglitol/mitiglinide combination is more potent than monotherapy in improving glycemic control through the reduction of postprandial glucose excursion and the simultaneous sparing of additional insulin secretion. A marked difference in the effects of miglitol and mitiglinide on incretin secretion was also demonstrated.

Ablation of 3-phosphoinositide-dependent protein kinase 1 (PDK1) in vascular endothelial cells enhances insulin sensitivity by reducing visceral fat and suppressing angiogenesis.

The phosphatidylinositol 3-kinase signaling pathway in vascular endothelial cells is important for systemic angiogenesis and glucose metabolism. In this study, we addressed the precise role of the 3-phosphoinositide-dependent protein kinase 1 (PDK1)-regulated signaling network in endothelial cells in vivo, using vascular endothelial PDK1 knockout (VEPDK1KO) mice. Surprisingly, VEPDK1KO mice manifested enhanced glucose tolerance and whole-body insulin sensitivity due to suppression of their hepatic glucose production with no change in either peripheral glucose disposal or even impaired vascular endothelial function at 6 months of age. When mice were fed a standard diet at 6 months of age and a high-fat diet at 3 months of age, hypertrophy of epididymal adipose tissues was inhibited, adiponectin mRNA was significantly increased, and mRNA of MCP1, leptin, and TNFα was decreased in the white adipose tissue of VEPDK1KO mice in comparison with controls. Consequently, both the circulating adiponectin levels and the activity of hepatic AMP-activated protein kinase were significantly increased, subsequently enhancing whole-body insulin sensitivity and energy expenditure with increased hepatic fatty acid oxidation in VEPDK1KO mice. These results provide the first in vivo evidence that lowered angiogenesis through the deletion of PDK1 signaling not only interferes with the growth of adipose tissue but also induces increased energy expenditure due to amelioration of the adipocytokine profile. This demonstrates an unexpected role of PDK1 signaling in endothelial cells on the maintenance of proper glucose homeostasis through the regulation of adipocyte development.

[A target of PPARgamma agonist: diabetes mellitus].

The members of the PPARgamma agonists, such as the thiazolidinediones, act as insulin sensitizer and improve insulin resistance. Several clinical studies have evaluated the efficacy of PPARgamma agonists in the management of insulin resistance and type 2 diabetes mellitus (T2DM). They are believed to improve insulin resistance by stimulating differentiation of small adipocytes, normalizing serum adipocytokine profile, and protecting pancreatic beta cells. They also possess powerful anti-atherogenic potency through amelioration of lipid profile and their anti-inflammatory effects. The PROactive study demonstrated that pioglitazone protects against hard end-point of macrovascular events in T2DM patients with previous macrovascular disease. A number of studies have also proven the potency of PPARgamma agonists in the prevention of onset of T2DM.

Molecular mechanism by which pioglitazone preserves pancreatic beta-cells in obese diabetic mice: evidence for acute and chronic actions as a PPARgamma agonist.

Pioglitazone preserves pancreatic beta-cell morphology and function in diabetic animal models. In this study, we investigated the molecular mechanisms by which pioglitazone protects beta-cells in diabetic db/db mice. In addition to the morphological analysis of the islets, gene expression profiles of the pancreatic islet were analyzed using laser capture microdissection and were compared with real-time RT-PCR of db/db and nondiabetic m/m mice treated with or without pioglitazone for 2 wk or 2 days. Pioglitazone treatment (2 wk) ameliorated dysmetabolism, increased islet insulin content, restored glucose-stimulated insulin secretion, and preserved beta-cell mass in db/db mice but had no significant effects in m/m mice. Pioglitazone upregulated genes that promote cell differentiation/proliferation in diabetic and nondiabetic mice. In db/db mice, pioglitazone downregulated the apoptosis-promoting caspase-activated DNase gene and upregulated anti-apoptosis-related genes. The above-mentioned effects of pioglitazone treatment were also observed after 2 days of treatment. By contrast, the oxidative stress-promoting NADPH oxidase gene was downregulated, and antioxidative stress-related genes were upregulated, in db/db mice treated with pioglitazone for 2 wk, rather than 2 days. Morphometric results for proliferative cell number antigen and 4-hydroxy-2-noneal modified protein were consistent with the results of gene expression analysis. The present results strongly suggest that pioglitazone preserves beta-cell mass in diabetic mice mostly by two ways; directly, by acceleration of cell differentiation/proliferation and suppression of apoptosis (acute effect); and indirectly, by deceleration of oxidative stress because of amelioration of the underlying metabolic disorder (chronic effect).

Gallbladder edema in type 1 diabetic patient due to delayed-type insulin allergy.

A 29-year-old woman was diagnosed as having type 1 diabetes mellitus and received insulin aspart and NPH insulin (NovolinN). On day 22, she had leg edema and right abdominal pain. The serum hepatobiliary enzyme levels were markedly elevated. Computed tomography revealed gallbladder edema. After an injection of human regular insulin and NPH insulin (HumacartN), the elevated liver enzyme levels were no longer observed. Challenge testing demonstrated that protamine was the cause of her allergy. Furthermore, tests revealed increased VEGF levels. This is an extremely rare case with a delayed-type protamine allergy caused by NovolinN resulting in gallbladder edema.

A pilot study suggests that the G/G genotype of resistin single nucleotide polymorphism at -420 may be an independent predictor of a reduction in fasting plasma glucose and insulin resistance by pioglitazone in type 2 diabetes.

The aim of this study was to determine the relation between the G/G genotype of a resistin gene promoter single nucleotide polymorphism (SNP) at -420 (rs1862513) and glycemic control by pioglitazone in type 2 diabetes. In Study 1, 121 type 2 diabetic patients were treated with pioglitazone (15 or 30 mg/day) for 12 weeks, in addition to previous medication. In Study 2, 63 patients who had been treated with pioglitazone for 12 weeks were examined retrospectively. In Study 1, multiple regression analysis revealed that the G/G but not C/G genotype was correlated with a reduction in fasting plasma glucose (FPG) and homeostasis model assessment of insulin resistance (HOMA-IR) compared to C/C. When adjusted for age, gender, and BMI, the G/G genotype was an independent factor for the reduction of FPG (P=0.020) and HOMA-IR (P =0.012). When studies 1 and 2 were combined by adjusting the studies, age, gender, and BMI, the reduction of HbA1c was correlated with the G/G genotype (beta=-0.511, P=0.044). Therefore, this pilot study suggests that the G/G genotype of resistin SNP -420 may be an independent predictor of the reduction of fasting plasma glucose and HOMA-IR by pioglitazone.

Molecular analysis of db gene-related pancreatic beta cell dysfunction; evidence for a compensatory mechanism inhibiting development of diabetes in the db gene heterozygote.

The db gene homozygous, but not heterozygous, mice develop diabetes with severe beta-cell damage. We investigated the molecular mechanism underlying db gene-associated pancreatic beta-cell dysfunction. Islet morphology, beta-cell function, and gene expression profiles specific for pancreatic islet cells were compared among db gene homozygous(db/db), heterozygous (db/m) and unrelated m/m mice. The beta-cell ratio decreased in db/db mice with age, but not in non-diabetic db/m and m/m mice. The islet insulin content was lower, but the triglyceride content was higher in db/db than other mice. The islet cell specific gene expression profiles analyzed by laser capture microdissection method and morphological findings suggested an augmentation of beta-cell apoptosis, oxidative stress and ER stress in db/db mice. Interestingly, insulin I and II, anti-apoptotic bcl-2, and proliferation promoting ERK-1 gene expressions were significantly upregulated in db/m mice. An impaired glucose tolerance was shown in m/m mice fed a high fat diet, but not in db/m mice, in which a higher insulin response and increased beta-cell mass were observed. Expressions of insulin I and II, bcl-2, and ERK-1 gene were increased in db/m mice, but not in m/m fed a high fat diet. The present results strongly suggest that the db gene heterozygote, but not homozygote, acquires a compensatory mechanism suppressing beta-cell apoptosis and augmenting the capacity of beta-cell function.