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To compare the effects of miglitol [an alpha-glucosidase inhibitor (AGI) absorbed in the intestine] and voglibose (an AGI not absorbed) on plasma glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels, 26 and 24 Japanese type 2 diabetic patients were randomly assigned to receive miglitol or voglibose, respectively. After 12-week administration of both drugs, during 2-h meal tolerance test, plasma glucose, serum insulin and total GIP were significantly decreased and active GLP-1 was significantly increased. Miglitol group showed a significantly lower total GIP level than voglibose group. Miglitol, but not voglibose, significantly reduced body weight (BW). In all participants, the relative change in BW was positively correlated with that of insulin significantly and of GIP with a weak tendency, but not of GLP-1. In conclusion, both drugs can enhance postprandial GLP-1 responses and reduce GIP responses. The significant BW reduction by miglitol might be attributable to its strong GIP-reducing efficacy., (© 2011 Blackwell Publishing Ltd.)

Aim: D-chiro-inositol (DCI) has been shown to prevent and reverse endothelial dysfunction in diabetic rats and rabbits. The present study evaluates the preventive effect of DCI on experimental diabetic neuropathy (DN)., Methods: Streptozotocin-induced (STZ) diabetic mice were treated by oral gavage for 60 days with DCI (20 mg/kg/12 h) or saline (NaCl 0.9%; 0.1 ml/10 g/12 h; Diab) and compared with euglycaemic groups treated with saline (0.1 ml/10 g/12 h; Eugly). We compared the response of the isolated sciatic nerve, corpora cavernosa or vas deferens to electrical stimulation., Results: The electrically evoked compound action potential of the sciatic nerve was greatly blunted by diabetes. The peak-to-peak amplitude (PPA) was decreased from 3.24 ± 0.7 to 0.9 ± 0.2 mV (p < 0.05), the conduction velocity (CV) of the first component was reduced from 46.78 ± 4.5 to 26.69 ± 3.8 ms (p < 0.05) and chronaxy was increased from 60.43 ± 1.9 to 69.67 ± 1.4 ms (p < 0.05). These parameters were improved in nerves from DCI-treated mice (p < 0.05). PPA in the DCI group was 5.79 ± 0.8 mV (vs. 0.9 ± 0.2 mV-Diab; p < 0.05) and CV was 45.91 ± 3.6 ms (vs. 26.69 ± 3.8 ms-Diab; p < 0.05). Maximal relaxation of the corpus cavernosum evoked by electrical stimulation (2-64 Hz) in the Diab group was 36.4 ± 3.8% compared to 65.4 ± 2.8% in Eugly and 59.3 ± 5.5% in the DCI group (p < 0.05). Maximal contraction obtained in the vas deferens was 38.0 ± 9.2% in Eugly and 11.5 ± 2.6% in Diab (decrease of 69.7%; p < 0.05), compared to 25.2 ± 2.3% in the DCI group (p < 0.05 vs. diabetic). Electron microscopy of the sciatic nerves showed prevention of neuronal damage., Conclusions: DCI has a neuroprotective action in both autonomic and somatic nerves in STZ-induced DN., (© 2011 Blackwell Publishing Ltd.)

Aim: To confirm the efficacy of vildagliptin in patients with type 2 diabetes (T2D) by testing the hypothesis that glycosylated haemoglobin (HbA1c) reduction with vildagliptin is superior to that with voglibose after 12 weeks of treatment., Methods: In this 12-week, randomized, double-blind, active-controlled, parallel-group study, the efficacy and safety of vildagliptin (50 mg bid, n = 188) was compared with that of voglibose (0.2 mg tid, n = 192) in patients with T2D who were inadequately controlled with diet and exercise., Results: The characteristics of two groups were well matched at baseline. The mean age, body mass index (BMI) and HbA1c were 59.1 years, 24.9 kg/m(2) and 7.6%, respectively. At baseline, fasting plasma glucose (FPG) and 2-h postprandial glucose (PPG) were 9.01 mmol/l (162.2 mg/dl) and 13.57 mmol/l (244.3 mg/dl), respectively. The adjusted mean change in HbA1c from baseline to endpoint was -0.95 +/- 0.04% in the vildagliptin-treated patients and -0.38 +/- 0.04% in those receiving voglibose (between-group change = 0.57 +/- 0.06%, 95% confidence interval (CI) (-0.68 to -0.46%), p < 0.001), showing that vildagliptin was superior to voglibose. Endpoint HbA1c < or = 6.5% was achieved in 51% vildagliptin-treated patients compared with 24% patients who were on voglibose (p < 0.001). Vildagliptin also exhibited significantly (p < 0.001) greater reduction compared with voglibose in both FPG [1.34 vs. 0.43 mmol/l (24.1 vs. 7.8 mg/dl)] and 2-h PPG [2.86 vs. 1.1 mmol/l (51.5 vs. 19.8 mg/dl)]. Overall adverse events (AEs) were lower in the vildagliptin-treated patients compared with that in the voglibose-treated patients (61.2 vs. 71.4%), with no incidence of hypoglycaemia and serious adverse events with vildagliptin. Gastrointestinal AEs were significantly lower with vildagliptin compared with that of the voglibose (18.6 vs. 32.8%; p = 0.002)., Conclusions: Vildagliptin (50 mg bid) showed superior efficacy and better tolerability compared with voglibose in Japanese patients with T2D.

Objective: To compare the efficacy and safety of sitagliptin (a dipeptidyl peptidase-4 inhibitor) and voglibose (an alpha-glucosidase inhibitor) monotherapy in Japanese patients with type 2 diabetes who have inadequate glycaemic control (HbA1c > or =6.5% and <10.0%) on diet and exercise., Methods: In a multi-center, randomized, double-blind, parallel-group study, 319 patients were randomized (1:1) to 12-week treatment with sitagliptin 50 mg once daily or voglibose 0.2 mg thrice daily before meals. The primary analysis assessed whether sitagliptin was non-inferior to voglibose in lowering HbA1c., Results: After 12 weeks, sitagliptin was non-inferior to voglibose for HbA1c-lowering efficacy. Furthermore, sitagliptin was superior to voglibose, providing significantly greater reductions in HbA1c from baseline [least squares mean changes in HbA1c [95% confidence intervals (CI)] = -0.7% (-0.8 to -0.6) and -0.3% (-0.4 to -0.2), respectively; between-group difference = -0.4% (-0.5 to -0.3), p < 0.001]. Sitagliptin was also superior to voglibose on other key efficacy endpoints, including change from baseline in 2-h postmeal glucose (-2.8 mmol/l vs. -1.8 mmol/l, p < 0.001) and fasting plasma glucose (-1.1 mmol/l vs. -0.5 mmol/l, p < 0.001). After 12 weeks, the incidences of clinical adverse experiences (AEs), drug-related AEs and gastrointestinal AEs in the sitagliptin group (48.5, 10.4 and 18.4%, respectively) were significantly (p < 0.05) lower than those in the voglibose group (64.7, 26.3 and 34.6%, respectively). The incidences of hypoglycaemia, serious AEs and discontinuations due to AEs were low and similar in both groups., Conclusions: In Japanese patients with type 2 diabetes, once-daily sitagliptin monotherapy showed greater efficacy and better tolerability than thrice-daily voglibose over 12 weeks.

Aim: Alogliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, and voglibose, an alpha-glucosidase inhibitor, have different but complementary mechanisms of action on glucagon-like peptide-1 (GLP-1) regulation and glucose-lowering effects. The present study evaluated the chronic effects of combination treatment with alogliptin and voglibose in prediabetic db/db mice., Methods: Alogliptin (0.03%) and voglibose (0.001%) alone or in combination were administered in the diet to prediabetic db/db mice., Results: After 3 weeks, voglibose treatment increased GLP-1 secretion (voglibose alone, 1.6-fold; alogliptin plus voglibose, 1.5-fold), while it decreased plasma glucose-dependent insulinotropic polypeptide (GIP) (voglibose alone, -30%; alogliptin plus voglibose, -29%). Alogliptin, voglibose and combination treatment decreased plasma DPP-4 activity by 72, 15 and additively by 80%, respectively, and increased plasma active GLP-1 levels by 4.5-, 1.8- and synergistically by 9.1-fold respectively. Combination treatment increased plasma insulin by 3.6-fold (alogliptin alone, 1.3-fold; voglibose alone, 1.8-fold), decreased plasma glucagon by 30% (alogliptin alone, 11%; voglibose alone, 8%), and prevented the development of diabetes, much more effectively than either agent alone. After 4 weeks, alogliptin, voglibose and combination treatment increased pancreatic insulin content by 1.6-, 3.4- and synergistically by 8.5-fold respectively. Furthermore, combination treatment resulted in an increased expression of insulin, pancreatic and duodenal homeobox 1 (PDX1) and glucose transporter 2 (GLUT2), and maintenance of normal beta/alpha-cell distribution in the pancreatic islet., Conclusions: Chronic treatment with alogliptin in combination with voglibose concurrently increased active GLP-1 circulation, increased insulin secretion, decreased glucagon secretion, prevented the onset of the disease, and preserved pancreatic beta-cells and islet structure in prediabetic db/db mice.

Congenital malformations are more common in infants of diabetic women than in children of non-diabetic women. The mechanisms behind diabetes-induced congenital anomalies are not known. Disturbed micronutrient metabolism, in concert with oxidative stress, has been suggested as a cause of diabetes-induced malformations by several studies. In experimental work, administration of inositol, arachidonic acid and several antioxidative compounds, as well as folic acid, to the embryo, has proven to attenuate the teratogenic effects of a diabetic environment. Future therapeutic efforts may include supplementation with antioxidants or micronutrients, such as folic acid, to the pregnant diabetic woman, although exact compounds and doses need to be determined.