Comprehensive Search for GPCR Compounds which Can Enhance MafA and/or PDX-1 Expression Levels Using a Small Molecule Compound Library.

It has been shown that chronic hyperglycemia gradually decreases insulin biosynthesis and secretion which is accompanied by reduced expression of very important insulin gene transcription factors MafA and PDX-1. Such phenomena are well known as ß-cell glucose toxicity. It has been shown that the downregulation of MafA and/or PDX-1 expression considerably explains the molecular mechanism for glucose toxicity. However, it remained unknown which molecules can enhance MafA and/or PDX-1 expression levels. In this study, we comprehensively searched for G protein-coupled receptor (GPCR) compounds which can enhance MafA and/or PDX-1 expression levels using a small molecule compound library in pancreatic ß-cell line MIN6 cells and islets isolated from nondiabetic C57BL/6 J mice and obese type 2 diabetic C57BL/KsJ-db/db mice. We found that fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in MIN6 cells. We confirmed that fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in islets from nondiabetic mice as well. Furthermore, these reagents more clearly enhanced MafA, PDX-1, or insulin expression levels in islets from obese type 2 diabetic db/db mice in which MafA and PDX-1 expression levels are reduced due to glucose toxicity. In conclusion, fulvestrant and dexmedetomidine hydrochloride increased MafA, PDX-1, or insulin expression levels in MIN6 cells and islets from nondiabetic mice and obese type 2 diabetic db/db mice. To the best of our knowledge, this is the first report showing some molecule which can enhance MafA and/or PDX-1 expression levels. Therefore, although further extensive study is necessary, we think that the information in this study could be, at least in part, useful at some point such as in the development of new antidiabetes medicine based on the molecular mechanism of ß-cell glucose toxicity in the future.

Efficacy and safety of pemafibrate in patients with hypertriglyceridemia in clinical settings: A retrospective study.

BACKGROUND AND AIMS: Recently, pemafibrate, a selective PPARα modulator, has been developed as a treatment for hypertriglyceridemia and has attracted much attention. The aims of this study were to evaluate the efficacy and safety of pemafibrate in hypertriglyceridemia patients under clinical settings. METHODS AND RESULTS: We evaluated changes in lipid profiles and various parameters before and after 24-week pemafibrate administration in patients with hypertriglyceridemia who had not previously taken fibrate medications. There were 79 cases included in the analysis. 24 weeks after the treatment with pemafibrate, TG was significantly reduced from 312 ± 226 to 167 ± 94 mg/dL. In addition, lipoprotein fractionation tests using PAGE method showed a significant decrease in the ratio of VLDL and remnant fractionations, which are TG-rich lipoproteins. After pemafibrate administration, body weight, HbA1c, eGFR, and CK levels were not changed, but liver injury indices such as ALT, AST, and γ-GTP were significantly improved. CONCLUSION: In this study, pemafibrate improved the metabolism of atherosclerosis-induced lipoproteins in hypertriglyceridemia patients. In addition, it showed no off-target effects such as hepatic and renal damage or rhabdomyolysis.

Case report of severe hypoglycemic alcoholic ketoacidosis: A possible pitfall in diagnosis of ketoacidosis.

BACKGROUNDS: Hypoglycemic alcoholic ketoacidosis is known to be one of the emergent diseases but its frequency is very low compared to hyperglycemic ketoacidosis or hyperosmolar hyperglycemic syndrome observed in subjects with diabetes mellitus. CASE PRESENTATION: We experienced a case who had alcoholic ketoacidosis and severe hypoglycemia after drinking too much alcohol without taking enough food for a long period of time. In this subject, plasma glucose level was as low as 25 mg/dL, and ketone bodies, especially 3-hydroxybutyrate, were markedly increased. In addition, in blood gas analysis, severe acidosis was observed and anion gap was increased. These points were compatible with hypoglycemia alcoholic ketoacidosis. CONCLUSIONS: When we examine subjects with ketoacidosis and hypoglycemia, we should bear in mind the possibility of hypoglycemic alcoholic ketoacidosis especially in subjects who drink too much alcohol without taking enough food for a long period of time.

Imeglimin exerts favorable effects on pancreatic ß-cells by improving morphology in mitochondria and increasing the number of insulin granules.

Imeglimin is a new anti-diabetic drug commercialized in Japan (Twymeeg®) and has been drawing much attention in diabetes research area as well as in clinical practice. In this study, we evaluated the effect of imeglimin on pancreatic ß-cells. First, single-dose administration of imeglimin enhanced insulin secretion from ß-cells and decreased blood glucose levels in type 2 diabetic db/db mice. In addition, single-dose administration of imeglimin significantly augmented insulin secretion in response to glucose from islets isolated from non-diabetic db/m mice. Second, during an oral glucose tolerance test 4-week chronic treatment with imeglimin enhanced insulin secretion and ameliorated glycemic control in diabetic db/db mice. Furthermore, the examination with electron microscope image showed that imeglimin exerted favorable effects on morphology in ß-cell mitochondria and substantially increased the number of insulin granules in type 2 diabetic db/db and KK-Ay mice. Finally, imeglimin reduced the percentage of apoptotic ß-cell death which was accompanied by reduced expression levels of various genes related to apoptosis and inflammation in ß-cells. Taken together, imeglimin directly enhances insulin secretion in response to glucose from ß-cells, increases the number of insulin granules, exerts favorable effects on morphology in ß-cell mitochondria, and reduces apoptotic ß-cell death in type 2 diabetic mice, which finally leads to amelioration of glycemic control.

Molecular Mechanism of Pancreatic ß-Cell Failure in Type 2 Diabetes Mellitus.

Various important transcription factors in the pancreas are involved in the process of pancreas development, the differentiation of endocrine progenitor cells into mature insulin-producing pancreatic ß-cells and the preservation of mature ß-cell function. However, when ß-cells are continuously exposed to a high glucose concentration for a long period of time, the expression levels of several insulin gene transcription factors are substantially suppressed, which finally leads to pancreatic ß-cell failure found in type 2 diabetes mellitus. Here we show the possible underlying pathway for ß-cell failure. It is likely that reduced expression levels of MafA and PDX-1 and/or incretin receptor in ß-cells are closely associated with ß-cell failure in type 2 diabetes mellitus. Additionally, since incretin receptor expression is reduced in the advanced stage of diabetes mellitus, incretin-based medicines show more favorable effects against ß-cell failure, especially in the early stage of diabetes mellitus compared to the advanced stage. On the other hand, many subjects have recently suffered from life-threatening coronavirus infection, and coronavirus infection has brought about a new and persistent pandemic. Additionally, the spread of coronavirus infection has led to various limitations on the activities of daily life and has restricted economic development worldwide. It has been reported recently that SARS-CoV-2 directly infects ß-cells through neuropilin-1, leading to apoptotic ß-cell death and a reduction in insulin secretion. In this review article, we feature a possible molecular mechanism for pancreatic ß-cell failure, which is often observed in type 2 diabetes mellitus. Finally, we are hopeful that coronavirus infection will decline and normal daily life will soon resume all over the world.

Persistent Hypoglycemia Induced by Long-acting Insulin Degludec.

A 58-year-old Japanese man was brought to the emergency room due to disturbance of consciousness. He regained consciousness on the day of admission and started taking hospital meals, but he needed intravenous glucose administration for eight days. The total amount of glucose administration was 4,464 g. It took over three weeks for exogenous insulin to be almost undetectable. While degludec binds to albumin and exerts glucose-lowering effects for a long time, the above-mentioned period of three weeks was consistent with the half-life of albumin. Hypoglycemia induced by massive dose of insulin degludec is persistent and prominent.

Syndrome of inappropriate secretion of thyroid-stimulating hormone in a subject with galactorrhea and menstrual disorder and undergoing infertility treatment: Case report.

RATIONALE: Syndrome of inappropriate secretion of thyroid-stimulating hormone (SITSH) is a rare cause of hyperthyroidism. Thyroid-stimulating hormone (TSH) levels are usually normal or high, and triiodothyronine (FT3) and free thyroxine (FT4) levels are usually high in subjects with SITSH. PATIENT CONCERN: A 37-year-old woman had experienced galactorrhea and menstrual disorder for a couple of years before. She had undergone infertility treatment in 1 year before, hyperthyroidism was detected and she was referred to our institution. DIAGNOSIS: She was suspected of having SITSH and was hospitalized at our institution for further examination. The data on admission were as follows: FT3, 4.62 pg/mL; FT4, 1.86 ng/dL; TSH, 2.55 µIU/mL. Although both FT3 and FT4 levels were high, TSH levels were not suppressed, which is compatible with SITSH. In addition, in brain contrast-enhanced magnetic resonance imaging, nodular lesions were observed in the pituitary gland with a diameter of approximately 10 mm. In the thyrotropin-releasing hormone load test, TSH did not increase at all, which was also compatible with TSH-secreting pituitary adenoma. In the octreotide load test, the TSH levels were suppressed. Based on these findings, we diagnosed this subject as SITSH. INTERVENTIONS: Hardy surgery was performed after the final diagnosis. In TSH staining of the resected pituitary adenoma, many TSH-producing cells were observed. These findings further confirmed the diagnosis of pituitary adenoma producing TSH. OUTCOMES: Approximately 2 months after the operation, TSH, FT3, and FT4 levels were normalized. Approximately 3 months after the operation, she became pregnant without any difficulty. LESSONS: We should consider the possibility of SITSH in subjects with galactorrhea, menstrual disorders, or infertility. In addition, we should recognize that it is very important to repeatedly examine thyroid function in subjects with galactorrhea, menstrual disorder, or infertility.

Amelioration of hypercalcemia by cinacalcet treatment in a subject with relapsing acquired hypocalciuric hypercalcemia: A case report.

RATIONALE: Hypocalciuric hypercalcemia is classified as acquired hypocalciuric hypercalcemia (AHH) and familial hypocalciuric hypercalcemia (FHH). While FHH is inherited as an autosomal dominant trait, AHH is one of the rare acquired diseases and is usually treated with prednisolone. Here, we report a case with relapsing AHH which was well controlled with cinacalcet therapy. PATIENT CONCERN: A 68-year-old Japanese man was referred to our institution because of hypercalcemia. Despite such hypercalcemia, he was almost asymptomatic. DIAGNOSTICS: We diagnosed him as AHH due to the following reason. First, the ratio of calcium (Ca)/creatinine clearance was very low which met the criteria. Second, there was no overt family history of hypercalcemia. Third, his serum Ca level was within the normal range 3 years before. Fourth, despite hypercalcemia, he was almost asymptomatic and had no evidence of primary hyperparathyroidism. INTERVENTIONS: Although it is known that steroid therapy is useful for AHH, optimal treatment remains unknown and cinacalcet therapy is very much limited for the treatment of AHH. In this subject, we introduced cinacalcet therapy for the treatment of relapsing AHH. OUTCOMES: Serum Ca and parathyroid hormone levels were normalized after such therapy with cinacalcet. CONCLUSIONS: We should bear in mind that cinacalcet treatment is effective for the treatment of relapsing AHH.

Idiopathic Bilateral Extraocular Myositis in a Subject With Poorly Controlled Type 2 Diabetes Mellitus: Case Report.

Background: Extraocular myositis is characterized by acute onset of orbital pain, extraocular muscle swelling, absence of thyroid disease, and effectiveness of steroid therapy. While oculomotor nerve paralysis is often observed in subjects with diabetes mellitus, extraocular muscle paralysis is very rare among various diabetic mononeuropathies. In addition, while most diabetic mononeuropathies are observed as sporadic and/or unilateral neuropathy, bilateral mononeuropathy is also very rare. Case presentation: A 58-year-old male visited our institution due to diplopia. He was diagnosed as type 2 diabetes mellitus about 10 years before and treated with oral diabetes agents. To examine the cause of his symptom, he was hospitalized in our institution. Slight ptosis was observed, and failure of adduction was observed in the right eye. Glycemic control was poor; HbA1c was 9.3%. Liver, renal, and thyroid function were within normal range. Immunoglobulin (Ig) G was slightly high, but IgA, IgM, and IgG4 were within normal range. Various antibodies were all negative. Angiotensin-converting enzyme level was within normal range. There were no abnormalities in brain magnetic resonance imaging (MRI). After admission, to alleviate glucose toxicity, we started insulin therapy. On day 17, adduction failure of the left eye was observed in addition to the right eye. Vertical movement was also impaired in both eyes. Slight ptosis was observed in both eyes, and the right eye was completely close. In orbital MRI, some high signal was detected in both extraocular muscles. We performed steroid pulse therapy twice. About 4 months later, ptosis and vertical and horizontal movements in both eyes were almost completely recovered. Finally, we diagnosed him as idiopathic bilateral extraocular myositis. Conclusions: We should bear in mind the possibility of idiopathic bilateral extraocular myositis especially in subjects with poor glycemic control, although its incident rate is extremely rare.

Switching From Daily DPP-4 Inhibitor to Once-Weekly GLP-1 Receptor Activator Dulaglutide Significantly Ameliorates Glycemic Control in Subjects With Poorly Controlled Type 2 Diabetes Mellitus: A Retrospective Observational Study.

Aim: At present, daily DPP-4 inhibitors are quite frequently prescribed in subjects with type 2 diabetes mellitus (T2DM). Recently, it has been drawing much attention that once-weekly incretin-based injection dulaglutide was developed. In this study, we aimed to examine the possible effects of once-weekly GLP-1 receptor activator (GLP-1RA) dulaglutide on glycemic control as well as various metabolic parameters. Methods: We made a direct comparison between the effect of daily DPP-4 inhibitor and once-weekly dulaglutide on glycemic control in "study 1 (pre-post comparison)" and set the control group using the propensity score matching method in "study 2". Results: In study 1, switching from daily DPP-4 inhibitor to dulaglutide significantly ameliorated glycemic control in subjects with T2DM. Such effects were more obvious in poorly controlled subjects. After 1:1 propensity score matching, the switching group improved glycemic control compared with the non-switching group in study 2. Conclusion: We should bear in mind that switching from daily DPP-4 inhibitor to once-weekly GLP-1RA dulaglutide exerts more favorable effects on glycemic control regardless of age, body weight, and duration of diabetes in subjects with T2DM, especially when we fail to obtain good glycemic control with daily DPP-4 inhibitor.

Efficacy and safety of adding ipragliflozin to insulin in Japanese patients with type 1 diabetes mellitus: a retrospective study.

Advances in insulin preparations and administration methods have produced a gradual improvement in glycemic control in patients with type 1 diabetes mellitus (DM). Nevertheless, glycated hemoglobin (HbA1c) levels in patients with type 1 DM are still poor compared to those in patients with type 2 DM. Here, we sought to assess the efficacy and safety of the sodium-glucose cotransporter 2 (SGLT2) inhibitor ipragliflozin (IPRA) in patients with type 1 DM. This study was retrospectively conducted with data from type 1 DM patients who had a history of IPRA therapy. The primary endpoint was HbA1c level at 24 weeks. The baseline characteristics of a total of 12 subjects were as follows: age, 50.1 ± 13.2 years; diabetes duration, 17.3 ± 10.5 years; body mass index (BMI), 22.9 ± 2.1 kg/m2; HbA1c, 8.8 ± 1.3%; and daily insulin dose, 0.60 ± 0.21 units/kg. IPRA decreased HbA1c levels to 8.2 ± 1.2% (p < 0.05) and reduced insulin dose to 0.52 ± 0.17 units/kg (p < 0.01) after 24 weeks. HbA1c value was particularly reduced in subjects with preserved C-peptide index. IPRA significantly reduced body weight by -1.4 ± 1.4 kg (p < 0.01) 16 weeks after starting treatment, with no further weight loss after 24 weeks. There were no instances of diabetic ketoacidosis or severe hypoglycemia. IPRA exerted beneficial effects on glycemic control without any severe adverse effects, and should be safe and effective when used in patients with type 1 DM with understanding of correspondence in sick day.

Multiple endocrine neoplasia type 1 with a frameshift mutation in its gene accompanied by a giant cervical lipoma and multiple fatty deposits in the pancreas: case report.

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) is a syndrome characterized by pituitary neoplasia, primary hyperparathyroidism and pancreatic endocrine tumor. Here we show a case of MEN1 with a germline frameshift mutation in its gene accompanied by a giant cervical lipoma and multiple fatty deposits in the pancreas. CASE PRESENTATION: A 28-year-old man noticed the decreased visual acuity of both eyes and visited our institution. Since he was diagnosed as visual disturbance and brain computer tomography (CT) showed a mass in the pituitary fossa, he was hospitalized in our institution. Endoscopic trans-sphenoidal hypophysectomy and total parathyroidectomy with auto-transplantation were performed, and a giant cervical lipoma was resected. Furthermore, in genetic search, we found a germline frameshift mutation in MEN1 gene leading to the appearance of a new stop codon. CONCLUSIONS: We should bear in m ind that giant skin lipoma and multiple abnormal fatty deposits in the pancreas could be complicated with MEN1.

Early combination therapy of empagliflozin and linagliptin exerts beneficial effects on pancreatic ß cells in diabetic db/db mice.

Effects of combination therapy of dipeptidyl peptidase-4 (DPP-4) inhibitor and sodium-glucose co-transporter 2 (SGLT2) inhibitor on ß-cells are still unclear, although combination agent of these two drugs has become common in clinical practice. Therefore, we aimed to elucidate the effects of DPP-4 inhibitor and/or SGLT2 inhibitor on ß-cell mass and function and compared their effects between in an early and advanced phase of diabetes. We used 7-week-old db/db mice as an early phase and 16-week-old mice as an advanced phase and treated them for 2 weeks with oral administration of linagliptin, empagliflozin, linagliptin + empagliflozin (L + E group), and 0.5% carboxymethylcellulose (Cont group). Blood glucose levels in Empa and L + E group were significantly lower than Cont group after treatment. In addition, ß-cell mass in L + E group was significantly larger than Cont group only in an early phase, accompanied by increased Ki67-positive ß-cell ratio. In isolated islets, mRNA expression levels of insulin and its transcription factors were all significantly higher only in L + E group in an early phase. Furthermore, mRNA expression levels related to ß-cell differentiation and proliferation were significantly increased only in L + E group in an early phase. In conclusion, combination of DPP-4 inhibitor and SGLT2 inhibitor exerts more beneficial effects on ß-cell mass and function, especially in an early phase of diabetes rather than an advanced phase.

Favorable Effects of GLP-1 Receptor Agonist against Pancreatic ß-Cell Glucose Toxicity and the Development of Arteriosclerosis: "The Earlier, the Better" in Therapy with Incretin-Based Medicine.

Fundamental pancreatic ß-cell function is to produce and secrete insulin in response to blood glucose levels. However, when ß-cells are chronically exposed to hyperglycemia in type 2 diabetes mellitus (T2DM), insulin biosynthesis and secretion are decreased together with reduced expression of insulin transcription factors. Glucagon-like peptide-1 (GLP-1) plays a crucial role in pancreatic ß-cells; GLP-1 binds to the GLP-1 receptor (GLP-1R) in the ß-cell membrane and thereby enhances insulin secretion, suppresses apoptotic cell death and increase proliferation of ß-cells. However, GLP-1R expression in ß-cells is reduced under diabetic conditions and thus the GLP-1R activator (GLP-1RA) shows more favorable effects on ß-cells at an early stage of T2DM compared to an advanced stage. On the other hand, it has been drawing much attention to the idea that GLP-1 signaling is important in arterial cells; GLP-1 increases nitric oxide, which leads to facilitation of vascular relaxation and suppression of arteriosclerosis. However, GLP-1R expression in arterial cells is also reduced under diabetic conditions and thus GLP-1RA shows more protective effects on arteriosclerosis at an early stage of T2DM. Furthermore, it has been reported recently that administration of GLP-1RA leads to the reduction of cardiovascular events in various large-scale clinical trials. Therefore, we think that it would be better to start GLP-1RA at an early stage of T2DM for the prevention of arteriosclerosis and protection of ß-cells against glucose toxicity in routine medical care.

A case of tamoxifen-induced hypertriglyceridemia monitoring the changes in lipoprotein fractions over time.

BACKGROUND: Tamoxifen, which is one of the selective estrogen receptor modulators (SERMs), can bring out life-threatening complication, e.g. hypertriglyceridemia-induced acute pancreatitis, although it is rare. We precisely report changes in lipoprotein metabolism before and after tamoxifen discontinuation because there have been few reports of it. CASE PRESENTATION: 47-year-old premenopausal woman with dyslipidemia, type 2 diabetes, nonalcoholic fatty liver disease and chronic kidney disease was prescribed tamoxifen as adjuvant therapy after operation of breast cancer. She experienced severe tamoxifen-induced hypertriglyceridemia several months after dosing tamoxifen. Before cessation of tamoxifen, lipoprotein fraction test revealed marked stagnation of VLDL and IDL metabolisms, resulting in severe hypertriglyceridemia (serum triglyceride level was 1881 mg/dL). Seven days after tamoxifen withdrawal, lipoprotein fraction test showed that the metabolisms of endogenous lipoproteins were changed drastically. CONCLUSIONS: From these results, we confirmed that tamoxifen certainly changes lipoprotein metabolism through suppression of post-heparin lipolytic activity. It is very important to evaluate the balance between benefit and risk before dosing tamoxifen and survey lipid profiles constantly during treatment to avoid life-threatening complication when prescription of tamoxifen is planned.

Roxadustat and thyroid-stimulating hormone suppression.

Hypoxia-inducible factor prolyl-hydroxylase inhibitors belong to a new class of orally administered drugs for treating anemia in patients with chronic kidney disease (CKD). The prevalence of hypothyroidism is disproportionately high in patients with CKD on hemodialysis. We report a rapid suppression of thyroid-stimulating hormone (TSH) and decrease in free triiodothyronine (T3) and free tetraiodothyronine levels after switching from darbepoetin alfa to roxadustat in a hemodialysis patient with hypothyroidism on levothyroxine therapy. This was reversed after stopping roxadustat. Roxadustat has structural similarity with T3 and is a selective activating ligand for thyroid hormone receptor-ß possibly suppressing TSH release.

Clinical Characteristics of Withdrawal of Basal Insulin Therapy Among Japanese Patients with Type 2 Diabetes: A Multicenter Retrospective Observational Study.

INTRODUCTION: This study aimed to examine retrospectively the clinical backgrounds of Japanese patients with type 2 diabetes (T2D) who successfully withdrew from insulin use after being started on basal insulin in an outpatient setting. METHODS: The study population comprised 376 insulin-naïve patients who were started on basal insulin (glargine U100, glargine U300, or degludec) for the management of T2D and followed the treatment regimen for at least 6 months in 13 institutions in Japan. The clinical courses of the study participants were compared based on outpatient clinic medical records for the three different types of basal insulin prescribed by categorizing the participants into two groups retrospectively: those who successfully withdrew from insulin therapy and those who did not, during a 6-month observation period. The clinical determinants for insulin withdrawal were assessed using a Cox proportional hazard model. RESULTS: Glycated hemoglobin was improved in all participants regardless of basal insulin type. Of the 376 study participants, 61 successfully withdrew from basal insulin therapy. After adjustment was made for several confounders, the positive determinant factors for successful withdrawal of insulin were short duration of diabetes and high body mass index at the start of study, and the negative determinant factor was use of insulin secretagogues at the start. The types of basal insulin used by the study participants were not significant determinants of successful insulin withdrawal in this study. CONCLUSIONS: Use of basal insulin is a powerful option for the treatment of T2D. In patients with high BMI and/or short duration of diabetes, short-term insulin therapy is a promising strategy for the treatment of T2D before the initiation of insulin secretagogues, since such patients have the potential to successfully withdraw from basal insulin use even in an outpatient setting.

Association between Grit Scales and adherence to regular hospital visits among Japanese patients with type 2 diabetes: Prospective observational study.

This study examined the association between Grit Scales and adherence to a schedule of regular hospital visits among Japanese type 2 diabetes patients. Patients with type 2 diabetes who visited the outpatient clinic as new patients comprised the study's participants. Self-administered Short Grit Scale data were obtained from 122 patients at the first consultation and were then observed for 1 year. As the results, 21 participants failed to attend the hospital. In a logistic regression analysis, the Grit Scale as a continuous variable was positively associated with adherence to regular clinical visits. Its odds ratio and 95% confidential interval was 9.68 and 2.87-32.65 (P = 0.0003). In conclusion, it is likely that the Grit Scale is closely associated with adherence to regular hospital visits among Japanese type 2 diabetes patients.

Unexpected Pleiotropic Effects of SGLT2 Inhibitors: Pearls and Pitfalls of This Novel Antidiabetic Class.

Sodium-glucose co-transporter 2 (SGLT2) inhibitors facilitate urine glucose excretion by reducing glucose reabsorption, leading to ameliorate glycemic control. While the main characteristics of type 2 diabetes mellitus are insufficient insulin secretion and insulin resistance, SGLT2 inhibitors have some favorable effects on pancreatic ß-cell function and insulin sensitivity. SGLT2 inhibitors ameliorate fatty liver and reduce visceral fat mass. Furthermore, it has been noted that SGLT2 inhibitors have cardio-protective and renal protective effects in addition to their glucose-lowering effect. In addition, several kinds of SGLT2 inhibitors are used in patients with type 1 diabetes mellitus as an adjuvant therapy to insulin. Taken together, SGLT2 inhibitors have amazing multifaceted effects that are far beyond prediction like some emerging magical medicine. Thereby, SGLT2 inhibitors are very promising as relatively new anti-diabetic drugs and are being paid attention in various aspects. It is noted, however, that SGLT2 inhibitors have several side effects such as urinary tract infection or genital infection. In addition, we should bear in mind the possibility of diabetic ketoacidosis, especially when we use SGLT2 inhibitors in patients with poor insulin secretory capacity.

Multifaceted Mechanisms of Action of Metformin Which Have Been Unraveled One after Another in the Long History.

While there are various kinds of drugs for type 2 diabetes mellitus at present, in this review article, we focus on metformin which is an insulin sensitizer and is often used as a first-choice drug worldwide. Metformin mainly activates adenosine monophosphate-activated protein kinase (AMPK) in the liver which leads to suppression of fatty acid synthesis and gluconeogenesis. Metformin activates AMPK in skeletal muscle as well, which increases translocation of glucose transporter 4 to the cell membrane and thereby increases glucose uptake. Further, metformin suppresses glucagon signaling in the liver by suppressing adenylate cyclase which leads to suppression of gluconeogenesis. In addition, metformin reduces autophagy failure observed in pancreatic ß-cells under diabetic conditions. Furthermore, it is known that metformin alters the gut microbiome and facilitates the transport of glucose from the circulation into excrement. It is also known that metformin reduces food intake and lowers body weight by increasing circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15). Furthermore, much attention has been drawn to the fact that the frequency of various cancers is lower in subjects taking metformin. Metformin suppresses the mechanistic target of rapamycin (mTOR) by activating AMPK in pre-neoplastic cells, which leads to suppression of cell growth and an increase in apoptosis in pre-neoplastic cells. It has been shown recently that metformin consumption potentially influences the mortality in patients with type 2 diabetes mellitus and coronavirus infectious disease (COVID-19). Taken together, metformin is an old drug, but multifaceted mechanisms of action of metformin have been unraveled one after another in its long history.