ObjectiveMetformin is known to have a beneficial effect on body weight and body composition, although the precise mechanism has not been elucidated yet. The aim of this study is to investigate the effects of metformin on energy metabolism and anthropometric factors in both human subjects and rats.MethodsIn human studies, metformin (1500mg/day) was administered to 23 healthy subjects and 18 patients with type 2 diabetes for 2 weeks. Metabolic parameters and energy metabolism were measured during a meal tolerance test in the morning before and after the treatment of metformin. In animal studies, 13 weeks old SD rats were fed 25–26 g of standard chow only during 12-hours dark phase with either treated by metformin (2.5mg/ml in drinking water) or not for 2 weeks, and metabolic parameters, anthropometric factors and energy metabolism together with expressions related to fat oxidation and adaptive thermogenesis were measured either in fasting or post-prandial state at 15 weeks old.ResultsPost-prandial plasma lactate concentration was significantly increased after the metformin treatment in both healthy subjects and diabetic patients. Although energy expenditure (EE) did not change, baseline respiratory quotient (RQ) was significantly decreased and post-prandial RQ was significantly increased vice versa following the metformin treatment in both groups. By the administration of metformin to SD rats for 2 weeks, plasma levels of lactate and pyruvate were significantly increased in both fasting and post-prandial states. RQ during a fasting state was significantly decreased in metformin-treated rats compared to controls with no effect on EE. Metformin treatment brought about a significant reduction of visceral fat mass compared to controls accompanied by an up-regulation of fat oxidation-related enzyme in the liver, UCP-1 in the brown adipose tissue and UCP-3 in the skeletal muscle.ConclusionFrom the results obtained, beneficial effects of metformin on visceral fat reduction has been demonstrated probably through a mechanism for a potential shift of fuel resource into fat oxidation and an upregulation of adaptive thermogenesis independent of an anorexigenic effect of this drug.

Aims/IntroductionTo assess the effects of sodium glucose co-transporter 2 inhibitor therapy on the pathophysiology of type 2 diabetes.Materials and MethodsWe administered ipragliflozin to 21 inpatients with type 2 diabetes for 7 days, and analyzed the diurnal profiles of plasma glucose and 3-hydroxybutyrate. A total of 21 age-, sex- and body mass index-matched diabetic patients served as controls.ResultsContinuous glucose monitoring showed that the 24-h glucose curve was shifted downward without hypoglycemia by the administration of ipragliflozin. The average glucose level was reduced from 182 ± 54 mg/dL to 141 ± 33 mg/dL (P < 0.0001). The magnitude of the reduction was highly correlated with the baseline average glucose level. Homeostasis model assessment of insulin resistance was decreased, and homeostasis model assessment of β-cell function was increased during the treatment. Urinary glucose excretion was correlated with the average glucose level both on day 0 and on day 7, although the regression line was steeper and shifted leftward on day 7. The ipragliflozin-treated patients lost more weight than the control patients (1.4 ± 0.5 vs 0.5 ± 0.6 kg, P < 0.0001). Plasma levels of 3-hydroxybutyrate were significantly increased with peaks before breakfast and before dinner. Patient age and bodyweight loss were negatively and positively correlated with the peak levels of 3-hydroxybutyrate on day 7, respectively.ConclusionsThe ipragliflozin treatment improved the 24-h glucose curve without causing hypoglycemia. The close correlation between the magnitude of glucose reduction and the baseline plasma glucose concentration suggests that the risk of hypoglycemia is likely low. It might be prudent to monitor ketone body levels in younger patients and in patients with rapid weight loss.

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Intravenous methylprednisolone (IVMP) pulse therapy is the first-line treatment for the active phase of moderate to severe Graves' orbitopathy (GO). However, acute and severe liver damage has been reported during and after IVMP therapy. In this retrospective study, we investigated risk factors for liver dysfunction during and after IVMP therapy based on 175 Japanese patients with moderate to severe GO and treated at our center between 2003 and 2011. The results showed that seven patients developed severe liver dysfunction with elevated serum alanine aminotransferase (ALT > 300 U/L). Mild (40–100 U/L) and moderate (100–300 U/L) increases of ALT occurred in 62 patients (35%) and 10 patients (6%), respectively. Liver dysfunction was more frequently observed in males, in patients receiving high-dose methylprednisolone, and patients aged over 50 years. Preexistent viral hepatitis was significantly associated with liver dysfunction (65% in patients positive for hepatitis B core antibody and patients positive for hepatitis C virus antibodies). Our study confirmed the association of liver dysfunction with IVMP during and after treatment. It suggests that, in patients with GO, evaluation of preexisting risk factors—including viral hepatitis—and careful weekly monitoring of liver function during IVMP therapy and monthly thereafter for 12 months are warranted.