Insulin-independent Manner Research Articles

Insulin-Independent GABAA Receptor-Mediated Response in the Barrel Cortex of Mice with Impaired Met Activity.

A proposed common cause of neurodevelopmental disorders is an imbalance in excitatory neural transmission, provided by the glutamatergic neurons, and the inhibitory signals from the GABAergic interneurons. Many genes associated with autism spectrum disorders impair synaptic transmission in the expected cell type. Previously, inactivation of the autism-associated Met tyrosine kinase receptor in GABAergic interneurons led to decreased inhibition. In thus report, decreased Met signaling in glutamatergic neurons had no effect on excitation, but decimated inhibition. Further experiments indicate that loss of Met activity downregulates GABAAreceptors on glutamatergic neurons in an insulin independent manner. These data provide a new mechanism for the loss of inhibition and subsequent abnormal excitation/inhibition balance and potential molecular candidates for treatment or prevention.

Protective Role of Sodium-Glucose Co-Transporter 2 Inhibition Against Vascular Complications in Diabetes.

Diabetic micro- and macroangiopathy are devastating vascular complications that could account for disabilities and high mortality rate in patients with diabetes. Indeed, diabetic nephropathy and retinopathy are the leading causes of end-stage renal failure and acquired blindness, respectively, and atherosclerotic cardiovascular diseases (CVD) accounts for about 60% of death in diabetic subjects. As a result, the average life span of diabetic patients is about 10-15 years shorter than that of non-diabetic subjects. Furthermore, tight blood glucose control might have no more than a marginal impact on CVD in general and on all-cause mortality in particular in diabetes. Therefore, therapeutic strategies that target vascular complications in diabetes need to be developed. Recently, selective inhibition of sodium-glucose co-transporter 2 (SGLT2) has been proposed as a potential therapeutic target for the treatment of patients with diabetes because of low risk of hypoglycemia and no weight gain. Because 90% of glucose filtered by the glomerulus is reabsorbed by a low-affinity/high-capacity SGLT2 expressed in the S1 and S2 segments of the proximal tubule, blockade of SGLT2 promotes urinary glucose excretion and as a result improves hyperglycemia in an insulin-independent manner. Moreover, we have shown that SGLT2-mediated glucose overload to tubular cells could elicit inflammatory and pro-apoptotic reactions in this cell, being directly involved in diabetic nephropathy. In addition, several clinical studies have also shown that SGLT2 inhibitors could reduce blood pressure, body weight, and serum uric acid levels and ameliorate cardiovascular risk in patients with diabetes. This review summarizes the pathophysiological role of SGLT2 in vascular complications in diabetes and its potential therapeutic interventions.

The Effects of Empagliflozin, an SGLT2 Inhibitor, on Pancreatic β-Cell Mass and Glucose Homeostasis in Type 1 Diabetes

The novel sodium glucose co-transporter 2 (SGLT2) inhibitor empagliflozin has recently been reported to improve glycemic control in streptozotocin-induced type 1 diabetic rats in an insulin-independent manner, via an increase in urinary glucose output. We investigated the potential of empagliflozin to recover insulin pathways in type 1 diabetes by improving pancreatic β-cell mass. Blood glucose homeostasis was assessed by an intraperitoneal glucose tolerance test. Serum insulin levels and insulin mRNA expression were determined using commercial insulin ELISA kits and real-time quantitative polymerase chain reaction, respectively. Immunohistochemistry was used to investigate β-cell areas, β-cell proliferation, apoptosis of pancreatic β-cells, and reactive oxygen species production in the pancreatic β-cells. Results showed that glucose tolerance was significantly improved in streptozotocin-induced type 1 diabetic mice treated with empagliflozin. Empagliflozin-treated mice also showed an increase in insulin mRNA expression. Higher serum insulin levels were detected in mice treated with empagliflozin compared with the vehicle group. Immunohistochemistry indicated that β-cell area/total pancreatic area and the expression of cell proliferation marker Ki-67 (co-stained with insulin) were significantly enhanced by empagliflozin treatment. These effects were due, probably, to a reduction in apoptosis and reactive oxygen species in the pancreatic β-cells. Taken together, the results of this study indicate that empagliflozin may have a beneficial effect on preserving β-cell regeneration, thus improving blood glucose homeostasis in type 1 diabetes mellitus, probably via the protection of pancreatic β-cell from glucotoxicity-induced oxidative stress.

Decreased insulin secretion and glucose clearance in exocrine pancreas-insufficient pigs.

The effect of exocrine pancreatic function on the glucose-mediated insulin response and glucose utilization were studied in an exocrine pancreas-insufficient (EPI) pig model. Five 10-week-old EPI pigs after pancreatic duct ligation and 6 age-matched, non-operated control pigs were used in the study. Blood glucose, plasma insulin and C-peptide concentrations were monitored during meal (MGTT), oral (OGTT) and intravenous (IVGTT) glucose tolerance tests. Upon post-mortem examination, the pancreatic remnants of the EPI pigs showed acinar fibrotic atrophy but normal islets and β-cell morphology. The EPI pigs displayed increased fasting glucose concentrations compared with control animals (6.4 ± 0.4 versus 4.8 ± 0.1 mmol l(-1) , P < 0.0001) but unchanged insulin concentrations (2.4 ± 0.6 versus 2.1 ± 0.2 pmol l(-1) ). During the OGTT and IVGTT, the EPI pigs showed slower, impaired glucose utilization, with the disruption of a well-timed insulin response. Plasma C-peptide concentrations confirmed the delayed insulin response during the IVGTT in EPI pigs. Oral pancreatic enzyme supplementation (PES) of EPI pigs improved glucose clearance during IVGTT [AUC(glucose) 1295 ± 70 mmol l(-1) × (120 min) in EPI versus 1044 ± 32 mmol l(-1) × (120 min) in EPI + PES, P < 0.0001] without reinforcing the release of insulin [AUC(C-peptide) 14.4 ± 3.8 nmol l(-1) × (120 min) in EPI versus 6.4 ± 1.3 nmol l(-1) × (120 min) in EPI + PES, P < 0.002]. The results suggest the existence of an acino-insular axis regulatory communication. The presence of pancreatic enzymes in the gut facilitates glucose utilization in an insulin-independent manner, indicating the existence of a gut-derived pancreatic enzyme-dependent mechanism involved in peripheral glucose utilization.

Sodium-Glucose Cotransporter 2 Inhibitors: Possible Anti-Atherosclerotic Effects Beyond Glucose Lowering.

The new drug for type 2 diabetes, the sodium-glucose cotransporter 2 (SGLT-2) inhibitor, is reversible inhibitor of SGLT-2, leading to reduction of renal glucose reabsorption and decrease of plasma glucose, in an insulin-independent manner. In addition to glucose control, the management of coronary risk factors is very important for patients with diabetes. Here we reviewed published articles about the possible anti-atherosclerotic effects beyond glucose lowering of the SGLT-2 inhibitors. We searched by using Pubmed, and found 770 published articles about SGLT-2 inhibitors. Among 10 kinds of SGLT-2 inhibitors, the number of published articles about dapagliflozin was the greatest among SGLT-2 inhibitors. Since SGLT-2 inhibitors have similar chemical structures, we concentrated on the published articles about dapagliflozin. SGLT-2 inhibitors are proved to be significantly associated with weight loss and reduction of blood pressure by a relatively large number of studies. The studies investigating effects of dapagliflozin on visceral fat, insulin sensitivity, serum lipids, inflammation and adipocytokines are very limited. An influence of increase in glucagon secretion by SGLT-2 inhibitors on metabolic risk factors remains unknown.

Management of Chronic Kidney Disease: The Relationship Between Serum Uric Acid and Development of Nephropathy

Chronic kidney disease (CKD) is increasingly recognized as a global health problem, and new and effective strategies are needed for the management of this condition. Recently, there has been renewed interest in the relationship between serum uric acid (SUA) levels and CKD, and several recent trials have demonstrated a possible link between SUA and the development and/or progression of CKD in patients with and without diabetes. The identification of key urate transporters such as urate transporter 1 and glucose transporter 9 has provided not only insights into the pathophysiology of hyperuricemia, but also possible links to other processes, such as glucose homeostasis. The renewed interest in the role of SUA in CKD has coincided with the development of sodium glucose co-transporter 2 inhibitors for the treatment of diabetes. In addition to improving glycemic control, these agents, acting via the kidneys in an insulin-independent manner, have also been shown to reduce SUA levels and potentially improve some measures of renal function. This review will discuss the role of uric acid in CKD treatment, and how SUA-lowering therapies may prevent or delay the progression of CKD. Funding: Janssen Scientific Affairs.Electronic supplementary materialThe online version of this article (doi:10.1007/s12325-015-0272-7) contains supplementary material, which is available to authorized users.

IGFBP7 is involved in abalone metamorphosis

Metamorphosis is the most critical life stage for abalone. There are morphogenetic transformations and habitat selection with metamorphosis. A large amount of larvae often die during this stage. Insulin/insulin-like growth factor signaling pathway (IIS) plays a role in the development. However, there is little knowledge of IIS function in metamorphosis. IGFBP7, a component of IIS, was found to be involved in metamorphosis of small abalone Haliotis diversicolor. The expression of saIGFBP7 mRNA rapidly increased before metamorphosis, which were mainly localized in the velum and foot. There was a significant decrease of metamorphosis rate after competent larvae were exposed to 5μg/mL dsRNA of saIGFBP7 (p=2.50×10−10, F=389.05). The expressions of three downstream genes of IIS (PI3K, ERKα and AKT) as well as saIGFBP7 were decreased in the dsRNA exposure experiment. There was no significant difference of metamorphosis rate (p=0.97, F=0.071) after competent larvae were induced in different concentrations of insulin. The expression of saIGFBP7, PI3K and ERKα also had no significant difference in insulin inducing assay. However, AKT expression level of 1μmol/L insulin induced group was significantly higher than that of other concentrations (p=3.41×10−7, F=26.68). These results suggested that IGFBP7 is involved in metamorphosis of abalone larvae. Our study provides insight on developing new methods for increasing the metamorphosis rate in abalone aquaculture. However, it does not work as a negative regulator of IIS activity, or plays its role in an IGF- and insulin-independent manner during metamorphosis of abalone larvae.

Sodium-Glucose Cotransporter 2 Inhibitors in the Treatment of Type 2 Diabetes Mellitus.

The purpose of this review article is to provide guidance to clinicians and diabetes educators regarding the use of sodium-glucose cotransporter 2 (SGLT2) inhibitors as a therapeutic option for the treatment of patients with type 2 diabetes mellitus (T2DM). The PubMed database was searched through February 2015 to identify clinical trials and meta-analyses evaluating the use of the SGLT2 inhibitors canagliflozin, dapagliflozin, and empagliflozin administered as monotherapy or in combination with other oral antidiabetes drugs or with insulin. SGLT2 inhibitors reduce hyperglycemia in an insulin-independent manner by inhibiting the reabsorption of glucose into the systemic circulation by the kidneys. In patients with T2DM, SGLT2 inhibitors provide consistent reductions in glycated hemoglobin, fasting plasma and postprandial glucose, body weight, and blood pressure when used as monotherapy or in combination with other oral antidiabetes agents or with insulin. SGLT2 inhibitors are associated with a low risk of hypoglycemia, except when used with agents known to be associated with a higher risk of hypoglycemia, such as sulfonylureas or insulin. The unique renal-specific mechanism of action and favorable efficacy and safety profile of SGLT2 inhibitors support consideration of these antidiabetes agents as a treatment option for patients with T2DM.

Tctex1d2 Is a Negative Regulator of GLUT4 Translocation and Glucose Uptake.

Tctex1d2 (Tctex1 domain containing 2) is an open reading frame that encodes for a functionally unknown protein that contains a Tctex1 domain found in dynein light chain family members. Examination of gene expression during adipogenesis demonstrated a marked increase in Tctex1d2 protein expression that was essentially undetectable in preadipocytes and markedly induced during 3T3-L1 adipocyte differentiation. Tctex1d2 overexpression significantly inhibited insulin-stimulated glucose transporter 4 (GLUT4) translocation and 2-deoxyglucose uptake. In contrast, Tctex1d2 knockdown significantly increased insulin-stimulated GLUT4 translocation and 2-deoxyglucose uptake. However, acute insulin stimulation (up to 30 min) in 3T3-L1 adipocytes with overexpression or knockdown of Tctex1d2 had no effect on Akt phosphorylation, a critical signal transduction target required for GLUT4 translocation. Although overexpression of Tctex1d2 had no significant effect on GLUT4 internalization, Tctex1d2 was found to associate with syntaxin 4 in an insulin-dependent manner and inhibit Doc2b binding to syntaxin 4. In addition, glucose-dependent insulinotropic polypeptide rescued the Tctex1d2 inhibition of insulin-stimulated GLUT4 translocation by suppressing the Tctex1d2-syntaxin 4 interaction and increasing Doc2b-Synatxin4 interactions. Taking these results together, we hypothesized that Tctex1d2 is a novel syntaxin 4 binding protein that functions as a negative regulator of GLUT4 plasma membrane translocation through inhibition of the Doc2b-syntaxin 4 interaction.

Two triterpeniods from Cyclocarya paliurus (Batal) Iljinsk (Juglandaceae) promote glucose uptake in 3T3-L1 adipocytes: The relationship to AMPK activation

PurposeThe current study investigated the efficacy of Cyclocarya paliurus chloroform extract (CPEC) and its two specific triterpenoids (cyclocaric acid B and cyclocarioside H) on the regulation of glucose disposal and the underlying mechanisms in 3T3-L1 adipocytes. MethodsMice and adipocytes were stimulated by macrophages-derived conditioned medium (Mac-CM) to induce insulin resistance. CPEC was evaluated in mice for its ability by oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). To investigate the hypoglycemic mechanisms of CPEC and its two triterpenoids, glucose uptake, AMP-activated protein kinase (AMPK) activation, inhibitor of NF-κB kinase β (IKKβ) phosphorylation and insulin signaling transduction were detected in 3T3-L1 adipocytes using 2-NBDG uptake assay and Western blot analysis. ResultsMac-CM, an inflammatory stimulus which induced the glucose and insulin intolerance, increased phosphorylation of IKKβ, reduced glucose uptake and impaired insulin sensitivity. CPEC and two triterpenoids improved glucose consumption and increased AMPK phosphorylation under basal and inflammatory conditions. Moreover, CPEC and its two triterpenoids not only enhanced glucose uptake in an insulin-independent manner, but also restored insulin-mediated protein kinase B (Akt) phosphorylation by reducing the activation of IKKβ and regulating insulin receptor substrate-1 (IRS-1) serine/tyrosine phosphorylation. These beneficial effects were attenuated by AMPK inhibitor compound C, implying that the effects may be associated with AMPK activation. ConclusionsCPEC and its two triterpenoids promoted glucose uptake in the absence of insulin, as well as ameliorated IRS-1/PI3K/Akt pathway by inhibiting inflammation. These effects were related to the regulation of AMPK activity.

Anti-diabetic effect of Capparis spinosa L. root extract in diabetic rats.

Diabetes mellitus is the most common metabolic disorders with severe impact on quality of life. Reducing serum glucose levels and normalization of serum lipid is of great clinical importance for treating diabetes. To our knowledge, there are not any evidences about the anti-diabetic action of capparis spinosa root. In the present study the effects of the C. spinosa root extract on diabetic metabolic disorders have been studied in experimental diabetes. Rats were divided into six groups: normal control (NC), diabetic control (DC), diabetic rats receiving 0.2, 0.4 g/kg of plant extract or 0.6 mg/kg glibenclamide (groups D0.2, D0.4 or DG respectively). A normal group of rats was also designed to receive 0.2 g/kg of plant extract (N0.2). Rats were rendered diabetic (streptozotocin 60 mg/kg, i.p.) and treated with 0.2, 0.4 g/ kg of plant extract or glibenclamide for four weeks. At the end of the experiment, blood was drawn through heart puncture under deep anesthesia. Weight was measured weekly, glucose levels were measured at the first and fourth week and lipid profiles, insulin and liver enzymes at the end of the study. Glucose levels significantly decreased after treating with plant extract (p=0.003). However, insulin levels did not increase in any treating groups. Plant extract could significantly raise HDL and reduce levels of LDL and liver enzymes (ALT and ALP). These results showed that C. spinosa root extract could improve diabetic related metabolic derangement such as hyperglycemia, dyslipidemia, and elevated liver markers in an insulin-independent manner.

Glucuretic effects and renal safety of dapagliflozin in patients with type 2 diabetes.

Dapagliflozin is a selective sodium-glucose cotransporter 2 (SGLT2) inhibitor approved as a treatment for type 2 diabetes mellitus (T2DM) in the United States, the European Union and other countries. Dapagliflozin increases renal glucose excretion in an insulin-independent manner, and its mechanism of action is complementary to those of other antidiabetes medications. When used as monotherapy or in combination with other oral antidiabetes medications or insulin, dapagliflozin improves glycemic measures in patients with T2DM. Dapagliflozin treatment is also associated with weight reduction and a decrease in blood pressure, both of which may be beneficial in patients with T2DM. Because of its mechanism of action, dapagliflozin has a low intrinsic propensity to cause hypoglycemia. Overall, dapagliflozin is well tolerated, with the frequency of most adverse events similar to that seen with placebo. Cases of genital infections and, in some studies, urinary tract infections have been more frequent in dapagliflozin-treated groups compared with placebo groups. In the clinical development program, more cases of newly diagnosed bladder cancer were reported for patients treated with dapagliflozin (0.17%) compared with placebo or comparator (0.03%). Although there were not enough cases to determine causality, dapagliflozin should not be used in patients with bladder cancer and should be used with caution in patients with a history of bladder cancer. Dapagliflozin may decrease glomerular filtration rate (GFR), especially in elderly patients and patients with impaired renal function. Renal function should be monitored before initiation of dapagliflozin. Dapagliflozin should not be used in patients with an estimated GFR <60 ml/min/1.73 m(2). No cardiovascular safety signals have been detected for dapagliflozin, and a long-term cardiovascular outcomes study is ongoing. Evidence from clinical trials suggests that dapagliflozin is a promising new treatment option for T2DM.

Living without insulin: the role of leptin signaling in the hypothalamus.

Since its discovery in 1922, insulin has been thought to be required for normal metabolic homeostasis and survival. However, this view would need to be revised as recent results from different laboratories have convincingly indicated that life without insulin is possible in rodent models. These data indicate that particular neuronal circuitries, which include hypothalamic leptin-responsive neurons, are empowered with the capability of permitting life in complete absence of insulin. Here, we review the neuronal and peripheral mechanisms by which leptin signaling in the central nervous system (CNS) regulates glucose metabolism in an insulin-independent manner.

The exocyst complex regulates free fatty acid uptake by adipocytes.

The exocyst is an octameric molecular complex that drives vesicle trafficking in adipocytes, a rate-limiting step in insulin-dependent glucose uptake. This study assessed the role of the exocyst complex in regulating free fatty acid (FFA) uptake by adipocytes. Upon differentiating into adipocytes, 3T3-L1 cells acquire the ability to incorporate extracellular FFAs in an insulin-dependent manner. A kinetic assay using fluoresceinated FFA (C12 dodecanoic acid) uptake allows the real-time monitoring of FFA internalization by adipocytes. The insulin-dependent uptake of C12 dodecanoic acid by 3T3-L1 adipocytes is mediated by Akt and phosphatidylinositol 3 (PI3)-kinase. Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes. Consistent with the roles played by Exo70 and Sec8 in FFA uptake, mCherry-tagged Exo70 and HA-tagged Sec8 partially colocalize with lipid droplets within adipocytes, suggesting their active roles in the development of lipid droplets. Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex. This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

IGF-1R signaling is essential for the proliferation of cultured mouse spermatogonial stem cells by promoting the G2/M progression of the cell cycle.

Culture of mouse spermatogonial stem cells (mSSCs) contributes to understanding the mechanisms of mammalian spermatogenesis. Several key growth factors such as GDNF and FGF2 have been known to be essential for the proliferation of cultured mSSCs. However, additional factors regulating SSC proliferation remain to be identified. In this study, we report that IGF-1R signaling is required for the proliferation of cultured mSSCs by promoting the G2/M progression of the cell cycle. IGF-1 and its receptor IGF-1R are expressed in cultured mSSCs as well as in isolated Sertoli cells and interstitial cells. Blockage of IGF-1R signaling either by knockdown of IGF-1R or by the IGF-1R-specific inhibitor picropodophyllin (PPP) significantly reduced the proliferation of mSSCs, increased their apoptosis, and impaired their stem cell activity in an insulin-independent manner. PPP treatment of mSSCs blocked the G2/M progression. In contrast, both GDNF withdrawal and FGF2 signaling blockade decreased the entry of mSSCs into their S phases. Consistently, IGF-1 promoted the G2/M progression of thymidine-treated mSSCs, which were arrested at G1/S boundary synchronously; while GDNF and/or FGF2 stimulated their entry into the S phase. Moreover, IGF-1 activated the phosphorylation of AKT but not that of ERK1/2 in mSSCs. These results indicate that IGF-1R signaling stimulates the proliferation of mSSCs using a distinct mechanism from those by GDNF and FGF2, and will contribute to the establishment of a chemically defined culture system.

CYP17 genotype modifies the impact of anthropometric variation on salivary estradiol in healthy women.

Several studies demonstrate that human ovarian function is responsive to the energetic environment, which has led to the development of theoretical models that explain this phenomenon. Although many genes are involved in ovarian hormone production, the possibility that genetic polymorphism may affect ovarian response to energetic conditions has not been considered. Cytochrome P450c17α is an enzyme that produces androgen precursors used to make estrogens during ovarian steroidogenesis, and is encoded by the CYP17 gene. A functionally significant variant within the promoter region of CYP17 has been linked to variation in steroid production, and some evidence suggests that this polymorphism could alter transcription of CYP17 in an insulin-dependent manner. We tested the hypothesis that the CYP17 variant affected the relationship between anthropometric measurements and salivary estradiol in healthy women in the United States (n = 28). PCR-RLFP analysis was used to genotype women for the genetic variant, and estradiol was assayed from saliva by EIA. Moderated regression analysis of these preliminary data revealed a significant interaction between waist-to-hip ratio and CYP17 genotype (P = 0.004). Our study provides evidence that gene-environment interactions should be considered in future adaptive models for human ovarian function. Moreover, our results stand to illuminate possible associations between this genetic variant and reproductive disease.

The role of fibroblast growth factor 21 in the pathogenesis of non-alcoholic fatty liver disease and implications for therapy

Non-alcoholic fatty liver disease (NAFLD) includes a cluster of liver disorders ranging from simple fatty liver to non-alcoholic steatohepatitis (NASH) and cirrhosis. Due to its liver and vascular complications, NAFLD has become a public health problem with high morbidity and mortality. The pathogenesis of NAFLD is considered a “multi-hit hypothesis” that involves lipotoxicity, oxidative stress, endoplasmic reticulum stress, a chronic inflammatory state and mitochondrial dysfunction. Fibroblast growth factor 21 (FGF21) is a member of the fibroblast growth factor family with multiple metabolic functions. FGF21 directly regulates lipid metabolism and reduces hepatic lipid accumulation in an insulin-independent manner. Several studies have shown that FGF21 can ameliorate the “multi-hits” in the pathogenesis of NAFLD. The administration of FGF21 reverses hepatic steatosis, counteracts obesity and alleviates insulin resistance in rodents and nonhuman primates. Using several strategies, we show that the reversal of simple fatty liver and NASH is mediated by activation of the FGF21 signaling pathway. In this review, we describe the molecular mechanisms involved in the onset and/or progression of NAFLD, and review the current literature to highlight the therapeutic procedures associated with the FGF21 signaling pathway for simple fatty liver and NASH, which are the two most important types of NAFLD.

Dapagliflozin in patients with type 2 diabetes mellitus.

Dapagliflozin is a selective and reversible inhibitor of sodium-glucose linked transporter type 2 (SGLT2), which mediates approximately 90% of active renal glucose reabsorption in the early proximal tubule of the kidney. Dapagliflozin significantly reduces glucose reabsorption and decreases serum glucose concentration in an insulin-independent manner. The decrease of glucose reabsorption by dapagliflozin has also been associated with a reduction in body weight. Furthermore, the drug modestly reduces blood pressure levels through weight loss and its action as osmotic diuretic. Dapagliflozin has been approved as monotherapy in patients with type 2 diabetes mellitus (T2DM) who cannot tolerate metformin or in combination with other antidiabetic drugs, with the exception of pioglitazone due to the theoretical increased risk of bladder cancer. The drug should not be prescribed in patients with moderate or severe renal impairment or in patients at risk for developing volume depletion. Dapagliflozin is associated with increased incidence of genital and lower urinary tract infections, but these infections are usually mild to moderate and respond to standard antimicrobial treatment. Based on current evidence, dapagliflozin is a useful drug for patients with T2DM with a favorable safety profile. However, further research regarding the effects of dapagliflozin on cardiovascular outcomes is needed.

Physiological mechanisms of action of incretin and insulin in regulating skeletal muscle metabolism.

Type II diabetes (T2D) is a progressive condition affecting approximately 350 million adults worldwide. Whilst skeletal muscle insulin resistance and beta-cell dysfunction are recognised causes of T2D, progressive loss of lean muscle mass (reducing surface area for glucose disposal area) in tandem with ageing-related adiposity (i.e. sarcopenic obesity) also plays an important role in driving hyperglycaemia progression. The anabolic effects of nutrition on the muscle are driven by the uptake of amino acids, into skeletal muscle protein, and insulin plays a crucial role in regulating this. Meanwhile glucagon-like peptide (GLP-1) and glucose- dependent insulinotropic peptide (GIP) are incretin hormones released from the gut into the bloodstream in response to macronutrients, and have an established role in enhancing insulin secretion. Intriguingly, endocrine functions of incretins were recently shown to extend beyond classical insulinotropic effects, with GLP-1/GIP receptors being found in extra-pancreatic cells i.e., skeletal muscle and peripheral (muscle) microvasculature. Since, incretins have been shown to modulate blood flow and muscle glucose uptake in an insulin-independent manner, incretins may play a role in regulating nutrient-mediated modulation of muscle metabolism and microvascular tone, independently of their insulinotropic effects. In this review we will discuss the role of skeletal muscle in glucose homeostasis, disturbances related to insulin resistance, regulation of skeletal muscle metabolism, muscle microvascular abnormalities and disturbances of protein (PRO) metabolism seen in old age and T2D. We will also discuss the emerging non-insulinotropic role of GLP-1 in modulating skeletal muscle metabolism and microvascular blood flow.

Associations between bone, fat tissue and metabolic control in children and adolescents with type 1 diabetes mellitus.

To investigate the relationship between bone-derived osteocalcin (OC), osteoprotegerin (OPG), Receptor Activator of Nuclear Factor NF-ĸB ligand (RANKL), and fat tissue-derived leptin and adiponectin with a clinical outcome of type 1 diabetes mellitus (T1DM) in children and adolescents. 78 patients (43 girls and 35 boys), aged 11.5±4.3 years with T1DM and 11 age- and BMI-matched controls were included into the study. Patients were divided into 3 groups according to HbA1c level, I - below 7% [53 mmol/mol], II - 7-9% [53-75 mmol/mol] and III - above 9% [75 mmol/mol]. Blood samples for biochemical measurements were drawn at 8.00 AM, when the patients were in a fasting state. HbA1c was measured by the standardized IFCC method. OC, OPG, RANKL, leptin and adiponectin were measured by ELISA. ANOVA, and multiple regression analysis were used for statistical analysis. Significant differences in leptin and osteocalcin levels between groups with different HbA1c values were observed (p=0.03, p=0.04). Multiple regression analysis adjusted for age showed that serum OC and leptin negatively correlated with HbA1c levels (r=-0.22, p=0.004 and r=-0.27, p=0.0001, respectively). In contrast, serum OPG correlated positively with HbA1c (r=0.26, p=0.02) as well as with adiponectin (r=0.26, p=0.02) and RANKL (r=0.27, p=0.02) levels. The correlation of OC with HbA1c was the strongest in group I - patients with good metabolic control of DM (r=-0.43, p=0.03). In that group, in multiple regression analysis adjusted for age and BMI leptin correlated positively with daily dose of insulin (r=0.52, r=0.009). In group II and III in multiple regression analysis adjusted for age and BMI OC correlated negatively with leptin (r=-0.37, p=0.01). Our data suggest significant relationships between bone, fat tissue and glucose metabolism in pediatric patients with T1DM. The results can confirm that poor metabolic control is associated with reduced bone formation. On the other hand fat and bone tissue can influence glucose metabolism, potentiality in insulin-dependent manner. From these data leptin or OC may be potentially used as additional therapeutic agents for T1DM.