Effect of sodium-glucose cotransporter 2 (SGLT2) inhibition on weight loss is partly mediated by liver-brain-adipose neurocircuitry

Sodium-glucose transporter 2 inhibitors and cardiovascular-kidney-metabolic syndrome: a narrative review

The Cardiovascular-Kidney-Metabolic (CKM) syndrome is a systemic disorder involving obesity, diabetes, chronic kidney disease (CKD), and cardiovascular disease, characterized by complex pathophysiological mechanisms that interact and lead to increased morbidity and mortality. In recent years, sodium-glucose transport protein 2 inhibitors (SGLT2i), as a new class of antidiabetic medications, have shown remarkable efficacy in the management of diabetes, renal and cardiovascular diseases. Research has confirmed their ability to reduce cardiovascular events and all-cause mortality. These inhibitors lower blood glucose levels by decreasing renal reabsorption of glucose and sodium, and offer multiple benefits, including lowering blood pressure, reducing body weight, exerting antioxidant, anti-inflammatory, and anti-fibrotic effects, as well as reducing proteinuria and improving glomerular filtration rate. These effects collectively contribute to the improvement of cardiovascular and renal health. Furthermore, SGLT2i have shown potential therapeutic roles at various stages of CKM syndrome, including improving cardiac function, slowing CKD progression, promoting weight loss, and improving lipid profiles. However, the precise mechanisms of action and off-target effects of SGLT2i still require further investigation to evaluate their efficacy and safety under different clinical conditions. Future research directions should include strategies for multiple disease management, combination therapy effects, interdisciplinary collaboration, and long-term follow-up studies to fully understand and optimize the application of SGLT2i in the treatment of CKM syndrome.

SGLT2 inhibitors for alleviating heart failure through non-hypoglycemic mechanisms

Sodium-glucose cotransporter-2 (SGLT2) inhibitors afford significant cardiovascular benefits to patients with diabetes mellitus and heart failure. Three large randomized clinical trials (EMPAREG-Outcomes, DECLARE-TIMI58, and DAPA-HF) have shown that SGLT2 inhibitors prevent cardiovascular events and reduce the risk of death and hospital admission resulting from heart failure. Patients without type 2 diabetes mellitus (T2DM) also experience a similar degree of cardiovascular benefit as those with T2DM do. SGLT2 inhibitors could improve cardiac function through potential non-hypoglycemic mechanisms, including the reduction of the circulatory volume load, regulation of energy metabolism, maintenance of ion homeostasis, alleviation of inflammation and oxidative stress, and direct inhibition of cardiac SGLT1 receptors and antimyocardial fibrosis. This article reviews the mechanism through which SGLT2 inhibitors prevent/alleviate heart failure through non-hypoglycemic pathways, to support their use for the treatment of heart failure in non-T2DM patients.

Hypothalamic sex-specific metabolic shift by canagliflozin during aging

The hypothalamus undergoes significant changes with aging and plays crucial roles in age-related metabolic alterations. Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are anti-diabetic agents that promote glucose excretion, and metabolic homeostasis. Recent studies have shown that a SGLT2i, Canagliflozin (Cana), can extend the median survival of genetically heterogeneous UM-HET3 male mice and improve central metabolic control via increases in hypothalamic insulin responsiveness in aged males, as well as reduced age-associated hypothalamic inflammation. We studied the long- and short-term effects of Cana on hypothalamic metabolic control in UM-HET3 mice. Starting the treatment from 7 months of age, we show that 4 weeks of Cana treatment significantly reduced body weight and fat mass in male but not female mice that was associated with enhanced glucose tolerance and insulin sensitivity observed by 12 months. Indirect calorimetry showed that Cana treatment increased energy expenditure in male, but not female mice, at 12 months of age. Long-term Cana treatment increased metabolic rates in both sexes, and markedly increasing formation of both orexigenic and anorexigenic projections to the paraventricular nucleus of the hypothalamus (PVH) mostly in females by 25 months. Hypothalamic RNA-sequencing analysis revealed increased sex-specific genes and signaling pathways related to insulin signaling, glycogen catabolic pathway, neuropeptide signaling, and mitochondrial function upregulated by Cana, with males showing a more pronounced and sustained effect on metabolic pathways at both age groups. Overall, our data provide critical evidence for sex-specific mechanisms that are affected by Cana during aging suggesting key targets of hypothalamic Cana-induced neuroprotection for metabolic control.

Canagliflozin protects the cardiovascular system through effects on the gut environment in non-diabetic nephrectomized rats

BACKGROUND

The gut produces toxins that contribute to the cardiovascular complications of chronic kidney disease. Canagliflozin, a sodium glucose cotransporter (SGLT) 2 inhibitor that is used as an anti-diabetic drug, has a weak inhibitory effect against SGLT1 and may affect the gut glucose concentration and environment.

METHODS

Here, we determined the effect of canagliflozin on the gut microbiota and the serum gut-derived uremic toxin concentrations in 5/6th nephrectomized (Nx) rats.

RESULTS

Canagliflozin increased the colonic glucose concentration and restored the number of Lactobacillus bacteria, which was low in Nx rats. In addition, the expression of tight junction proteins in the ascending colon was low in Nx rats, and this was partially restored by canagliflozin. Furthermore, the serum concentrations of gut-derived uremic toxins were significantly increased by Nx and reduced by canagliflozin. Finally, the wall of the thoracic aorta was thicker and there was more cardiac interstitial fibrosis in Nx rats, and these defects were ameliorated by canagliflozin.

CONCLUSIONS

The increases in colonic glucose concentration, Lactobacillus numbers and tight junction protein expression, and the decreases in serum uremic toxin concentrations and cardiac interstitial fibrosis may have been caused by the inhibition of SGLT1 by canagliflozin because similar effects were not identified in tofogliflozin-treated rats.

Unlocking the Full Potential of SGLT2 Inhibitors: Expanding Applications beyond Glycemic Control

The number of diabetic patients has risen dramatically in recent decades, owing mostly to the rising incidence of type 2 diabetes mellitus (T2DM). Several oral antidiabetic medications are used for the treatment of T2DM including, α-glucosidases inhibitors, biguanides, sulfonylureas, meglitinides, GLP-1 receptor agonists, PPAR-γ agonists, DDP4 inhibitors, and SGLT2 inhibitors. In this review we focus on the possible effects of SGLT2 inhibitors on different body systems. Beyond the diabetic state, SGLT2 inhibitors have revealed a demonstrable ability to ameliorate cardiac remodeling, enhance myocardial function, and lower heart failure mortality. Additionally, SGLT2 inhibitors can modify adipocytes and their production of cytokines, such as adipokines and adiponectin, which enhances insulin sensitivity and delays diabetes onset. On the other hand, SGLT2 inhibitors have been linked to decreased total hip bone mineral deposition and increased hip bone resorption in T2DM patients. More data are needed to evaluate the role of SGLT2 inhibitors on cancer. Finally, the effects of SGLT2 inhibitors on neuroprotection appear to be both direct and indirect, according to scientific investigations utilizing various experimental models. SGLT2 inhibitors improve vascular tone, elasticity, and contractility by reducing oxidative stress, inflammation, insulin signaling pathways, and endothelial cell proliferation. They also improve brain function, synaptic plasticity, acetylcholinesterase activity, and reduce amyloid plaque formation, as well as regulation of the mTOR pathway in the brain, which reduces brain damage and cognitive decline.

The effects of Sodium-glucose cotransporter 2 inhibitors on adipose tissue in patients with type 2 diabetes: A meta-analysis of randomized controlled trials

PURPOSE

To systematically evaluate the effect of Sodium-glucose cotransporter 2 (SGLT2) inhibitors on adipose tissue in patients with type 2 diabetes.

METHODS

We searched PubMed, Cochrane Library, EMBASE, and Web of science databases for literature pertaining to Randomized controlled trials (RCTs) of SGLT2 inhibitors in treating type 2 diabetes patients. The retrieval time was from the date of establishment of the databases to September 1, 2022. Meta-analysis was performed using RevMan5.4 software.

RESULTS

Totally 551 patients were included in 10 articles. Meta-analysis results showed that compared with the control group, the visceral adipose tissue (WMD = -16.29 cm², 95% CI: -25.07 ~ -7.50, P<0.00001), subcutaneous adipose tissue (WMD = -19.34 cm², 95% CI: -36.27 ~ -2.41, P<0.00001), body weight (WMD = -2.36 kg, 95% CI: -2.89 ~ -1.83, P<0.00001) and triglyceride (WMD = -24.41 mg/dl, 95% CI: -45.79 ~ -3.03, P = 0.03) of the trial group significantly reduced.

CONCLUSION

SGLT2 inhibitors cause significant reductions in visceral adipose tissue, subcutaneous adipose tissue, body weight and triglycerides in type 2 diabetes patients, which may be attributed to the protective effect of the inhibitors on cardiovascular system.

The Neuronal and Non-Neuronal Pathways of Sodium-Glucose Cotransporter-2 Inhibitor on Body Weight-Loss and Insulin Resistance

With the emergence of sodium-glucose cotransporter 2 inhibitors (SGLT2i), the treatment of type 2 diabetes mellitus (T2DM) has achieved a new milestone, of which the insulin-independent mechanism could produce weight loss, improve insulin resistance (IR) and exert other protective effects. Besides the well-acknowledged biochemical processes, the dysregulated balance between sympathetic and parasympathetic activity may play a significant role in IR and obesity. Weight loss caused by SGLT-2i could be achieved via activating the liver-brain-adipose neural axis in adipocytes. We previously demonstrated that SGLT-2 are widely expressed in central nervous system (CNS) tissues, and SGLT-2i could inhibit central areas associated with autonomic control through unidentified pathways, indicating that the role of the central sympathetic inhibition of SGLT-2i on blood pressure and weight loss. However, the exact pathway of SGLT2i related to these effects and to what extent it depends on the neural system are not fully understood. The evidence of how SGLT-2i interacts with the nervous system is worth exploring. Therefore, in this review, we will illustrate the potential neurological processes by which SGLT2i improves IR in skeletal muscle, liver, adipose tissue, and other insulin-target organs via the CNS and sympathetic nervous system/parasympathetic nervous system (SNS/PNS).

Cardiovascular protection by SGLT2 inhibitors - Do anti-inflammatory mechanisms play a role?

BACKGROUND

Metabolic syndrome and related metabolic disturbances represent a state of low-grade inflammation, which accelerates insulin resistance, type 2 diabetes (T2D) and cardiovascular disease (CVD) progression. Among antidiabetic medications, sodium glucose co-transporter (SGLT) 2 inhibitors are the only agents which showed remarkable reductions in heart failure (HF) hospitalizations and major cardiovascular endpoints (MACE) as well as renal endpoints regardless of diabetes status in large randomized clinical outcome trials (RCTs). Although the exact mechanisms underlying these benefits are yet to be established, growing evidence suggests that modulating inflammation by SGLT2 inhibitors may play a key role.

SCOPE OF REVIEW

In this manuscript, we summarize the current knowledge on anti-inflammatory effects of SGLT2 inhibitors as one of the mechanisms potentially mediating their cardiovascular (CV) benefits. We introduce the different metabolic and systemic actions mediated by these agents which could mitigate inflammation, and further present the signalling pathways potentially responsible for their proposed direct anti-inflammatory effects. We also discuss controversies surrounding some of these mechanisms.

MAJOR CONCLUSIONS

SGLT2 inhibitors are promising anti-inflammatory agents by acting either indirectly via improving metabolism and reducing stress conditions or via direct modulation of inflammatory signalling pathways. These effects were achieved, to a great extent, in a glucose-independent manner which established their clinical use in HF patients with and without diabetes.

Sodium Glucose Cotransporter-2 Inhibitors: Spotlight on Favorable Effects on Clinical Outcomes beyond Diabetes

Sodium glucose transporter type 2 (SGLT2) molecules are found in proximal tubules of the kidney, and perhaps in the brain or intestine, but rarely in any other tissue. However, their inhibitors, intended to improve diabetes compensation, have many more beneficial effects. They improve kidney and cardiovascular outcomes and decrease mortality. These benefits are not limited to diabetics but were also found in non-diabetic individuals. The pathophysiological pathways underlying the treatment success have been investigated in both clinical and experimental studies. There have been numerous excellent reviews, but these were mostly restricted to limited aspects of the knowledge. The aim of this review is to summarize the known experimental and clinical evidence of SGLT2 inhibitors' effects on individual organs (kidney, heart, liver, etc.), as well as the systemic changes that lead to an improvement in clinical outcomes.

Empagliflozin Improves Insulin Sensitivity of the Hypothalamus in Humans With Prediabetes: A Randomized, Double-Blind, Placebo-Controlled, Phase 2 Trial

OBJECTIVE

Insulin action in the human brain reduces food intake, improves whole-body insulin sensitivity, and modulates body fat mass and its distribution. Obesity and type 2 diabetes are often associated with brain insulin resistance, resulting in impaired brain-derived modulation of peripheral metabolism. So far, no pharmacological treatment for brain insulin resistance has been established. Since sodium-glucose cotransporter 2 (SGLT2) inhibitors lower glucose levels and modulate energy metabolism, we hypothesized that SGLT2 inhibition may be a pharmacological approach to reverse brain insulin resistance.

RESEARCH DESIGN AND METHODS

In this randomized, double-blind, placebo-controlled clinical trial, 40 patients (mean ± SD; age 60 ± 9 years; BMI 31.5 ± 3.8 kg/m2) with prediabetes were randomized to receive 25 mg empagliflozin every day or placebo. Before and after 8 weeks of treatment, brain insulin sensitivity was assessed by functional MRI combined with intranasal administration of insulin to the brain.

RESULTS

We identified a significant interaction between time and treatment in the hypothalamic response to insulin. Post hoc analyses revealed that only empagliflozin-treated patients experienced increased hypothalamic insulin responsiveness. Hypothalamic insulin action significantly mediated the empagliflozin-induced decrease in fasting glucose and liver fat.

CONCLUSIONS

Our results corroborate insulin resistance of the hypothalamus in humans with prediabetes. Treatment with empagliflozin for 8 weeks was able to restore hypothalamic insulin sensitivity, a favorable response that could contribute to the beneficial effects of SGLT2 inhibitors. Our findings position SGLT2 inhibition as the first pharmacological approach to reverse brain insulin resistance, with potential benefits for adiposity and whole-body metabolism.

Sodium-Glucose Co-Transporter-2 Inhibitors in Non-Diabetic Adults With Overweight or Obesity: A Systematic Review and Meta-Analysis

BACKGROUND

Sodium-glucose-cotransporter-2 (SGLT2) inhibitors have proven to be effective in improving glycemic control and lowering body weight in patients with type 2 diabetes mellitus. However, the efficacy and safety on weight loss in adults with overweight or obesity but not diabetes remain unclear. In this article, we aimed to identify the efficacy and safety of SGLT2 inhibitors in adults with overweight or obesity but not diabetes in randomized controlled studies (RCTs).

METHODS

We searched for RCTs concerning SGLT2 inhibitors in adults with overweight or obesity but not diabetes in Medline (Ovid SP), Embase (Ovid SP), Cochrane Central Register of Controlled Trials (Ovid SP), and ClinicalTrials.gov up to February 2021. The primary outcomes were changes in body weight and body mass index (BMI). Trial sequential analysis (TSA) was used to test the reliability of the primary outcomes. We analyzed the data using Review Manager 5.3 and pooled data to calculate the mean differences (MDs) or the relative risk (RR). We assessed the evidence quality of evidence of outcomes according to GRADE.

RESULTS

Six randomized controlled trials involving 872 individuals were included in the meta-analysis. Compared to the placebo group, the SGLT2 inhibitors group had statistically significant reductions in absolute changes in body weight (MD: -1.42 kg, 95% CI: -1.70 to -1.14; P<0.00001) and BMI (MD: -0.47 kg/m2, 95% CI: -0.63 to -0.31; P<0.00001) in SGLT2 inhibitors group, as indicated by TSA. However, no significant benefits were observed in the SGLT2 inhibitors group in terms of waist circumference (MD: -1.34 cm, 95%CI: -2.75 to 0.07; Z=1.86, P=0.06) compared with the placebo group. The GRADE profiles indicated very low-quality evidence for body weight change and low-quality evidence for BMI change. SGLT2 inhibitors were generally safe and well tolerated.

CONCLUSION

SGLT2 inhibitors could be used in selected adults with overweight and obesity but not diabetes if they are at low risk of genital infection and urinary infection. Further studies are warranted to confirm the efficacy and safety of SGLT2 inhibitors in adults with overweight or obesity but not diabetes for long-term weight management.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/#loginpage], identifier [PROSPERO, CRD42021252931].

Ipragliflozin Improves the Hepatic Outcomes of Patients With Diabetes with NAFLD

Sodium glucose cotransporter‐2 inhibitors (SGLT2is) are now widely used to treat diabetes, but their effects on nonalcoholic fatty liver disease (NAFLD) remain to be determined. We aimed to evaluate the effects of SGLT2is on the pathogenesis of NAFLD. A multicenter, randomized, controlled trial was conducted in patients with type 2 diabetes with NAFLD. The changes in glycemic control, obesity, and liver pathology were compared between participants taking ipragliflozin (50 mg/day for 72 weeks; IPR group) and participants being managed without SGLT2is, pioglitazone, glucagon‐like peptide‐1 analogs, or insulin (CTR group). In the IPR group (n = 25), there were significant decreases in hemoglobin A1c (HbA1c) and body mass index (BMI) during the study (HbA1c, −0.41%, P < 0.01; BMI, −1.06 kg/m², P < 0.01), whereas these did not change in the CTR group (n = 26). Liver pathology was evaluated in 21/25 participants in the IPR/CTR groups, and hepatic fibrosis was found in 17 (81%) and 18 (72%) participants in the IPR and CTR groups at baseline. This was ameliorated in 70.6% (12 of 17) of participants in the IPR group and 22.2 % (4 of 18) of those in the CTR group (P < 0.01). Nonalcoholic steatohepatitis (NASH) resolved in 66.7% of IPR‐treated participants and 27.3% of CTR participants. None of the participants in the IPR group developed NASH, whereas 33.3% of the CTR group developed NASH. Conclusion: Long‐term ipragliflozin treatment ameliorates hepatic fibrosis in patients with NAFLD. Thus, ipragliflozin might be effective for the treatment and prevention of NASH in patients with diabetes, as well as improving glycemic control and obesity. Therefore, SGLT2is may represent a therapeutic choice for patients with diabetes with NAFLD, but further larger studies are required to confirm these effects.

Treatment with a β-2-adrenoceptor agonist stimulates glucose uptake in skeletal muscle and improves glucose homeostasis, insulin resistance and hepatic steatosis in mice with diet-induced obesity

AIMS/HYPOTHESIS

Chronic stimulation of β₂-adrenoceptors, opposite to acute treatment, was reported to reduce blood glucose levels, as well as to improve glucose and insulin tolerance in rodent models of diabetes by essentially unknown mechanisms. We recently described a novel pathway that mediates glucose uptake in skeletal muscle cells via stimulation of β₂-adrenoceptors. In the current study we further explored the potential therapeutic relevance of β₂-adrenoceptor stimulation to improve glucose homeostasis and the mechanisms responsible for the effect.

METHODS

C57Bl/6N mice with diet-induced obesity were treated both acutely and for up to 42 days with a wide range of clenbuterol dosages and treatment durations. Glucose homeostasis was assessed by glucose tolerance test. We also measured in vivo glucose uptake in skeletal muscle, insulin sensitivity by insulin tolerance test, plasma insulin levels, hepatic lipids and glycogen.

RESULTS

Consistent with previous findings, acute clenbuterol administration increased blood glucose and insulin levels. However, already after 4 days of treatment, beneficial effects of clenbuterol were manifested in glucose homeostasis (32% improvement of glucose tolerance after 4 days of treatment, p < 0.01) and these effects persisted up to 42 days of treatment. These favourable metabolic effects could be achieved with doses as low as 0.025 mg kg^-1 day^-1 (40 times lower than previously studied). Mechanistically, these effects were not due to increased insulin levels, but clenbuterol enhanced glucose uptake in skeletal muscle in vivo both acutely in lean mice (by 64%, p < 0.001) as well as during chronic treatment in diet-induced obese mice (by 74%, p < 0.001). Notably, prolonged treatment with low-dose clenbuterol improved whole-body insulin sensitivity (glucose disposal rate after insulin injection increased up to 1.38 ± 0.31%/min in comparison with 0.15 ± 0.36%/min in control mice, p < 0.05) and drastically reduced hepatic steatosis (by 40%, p < 0.01) and glycogen (by 23%, p < 0.05).

CONCLUSIONS/INTERPRETATION

Clenbuterol improved glucose tolerance after 4 days of treatment and these effects were maintained for up to 42 days. Effects were achieved with doses in a clinically relevant microgram range. Mechanistically, prolonged treatment with a low dose of clenbuterol improved glucose homeostasis in insulin resistant mice, most likely by stimulating glucose uptake in skeletal muscle and improving whole-body insulin sensitivity as well as by reducing hepatic lipids and glycogen. We conclude that selective β₂-adrenergic agonists might be an attractive potential treatment for type 2 diabetes. This remains to be confirmed in humans. Graphical abstract.

Diabetes, and its treatment, as an effector of autonomic nervous system circuits and its functions

Diabetes increases the risk of cardiovascular complications, including heart failure, hypertension, and stroke. There is a strong involvement of autonomic dysfunction in individuals with diabetes that exhibit clinical manifestations of cardiovascular diseases (CVD). Still, the mechanisms by which diabetes and its treatments alter autonomic function and subsequently affect cardiovascular complications remain elusive. For this reason, understanding the brainstem circuits involved in sensing metabolic state(s) and enacting autonomic control of the cardiovascular system are important to develop more comprehensive therapies for individuals with diabetes at increased risk for CVD. We review how autonomic nervous system circuits change during these disease states and discuss their potential role in current pharmacotherapies that target diabetic states. Overall, this review proposes that the brainstem circuits provide an integrative sensorimotor network capable of responding to metabolic cues to regulate cardiovascular function and this network is modified by, and in turn affects, diabetes-induced CVD and its treatment.

Combined effect of canagliflozin and exercise training on high-fat diet-fed mice

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have been reported to improve obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) in addition to exercise training, whereas the combined effects remain to be elucidated fully. We investigated the effect of the combination of the SGLT2i canagliflozin (CAN) and exercise training in high-fat diet-induced obese mice. High-fat diet-fed mice were housed in normal cages (sedentary; Sed) or wheel cages (WCR) with or without CAN (0.03% of diet) for 4 wk. The effects on obesity, glucose metabolism, and hepatic steatosis were evaluated in four groups (Control/Sed, Control/WCR, CAN/Sed, and CAN/WCR). Numerically additive improvements were found in body weight, body fat mass, blood glucose, glucose intolerance, insulin resistance, and the fatty liver of the CAN/WCR group, whereas CAN increased food intake and reduced running distance. Exercise training alone, CAN alone, or both did not change the weight of skeletal muscle, but microarray analysis showed that each resulted in a characteristic change of gene expression in gastrocnemius muscle. In particular, in the CAN/WCR group, there was acceleration of the angiogenesis pathway and suppression of the adipogenesis pathway compared with the CAN/Sed group. In conclusion, the combination of an SGLT2i and exercise training improves obesity, insulin resistance, and NAFLD in an additive manner. Changes of gene expression in skeletal muscle may contribute, at least in part, to the improvement of obesity and insulin sensitivity.

Reinterpreting Cardiorenal Protection of Renal Sodium-Glucose Cotransporter 2 Inhibitors via Cellular Life History Programming

Cardiovascular outcome trials have provided evidence that sodium-glucose cotransporter 2 inhibitor (SGLT2i) treatment is associated with remarkably favorable cardiovascular outcomes. Here, we offer a novel hypothesis that may encompass many of these hypothetical mechanisms, i.e., the ability of SGLT2i to modify the trajectory of cell response to a toxic environment through modifications of cellular life history programs, either the defense program or the dormancy program. The choice between these programs is mainly determined by the environment. Hyperglycemia can be considered a toxic determinant able to interfere with the basic programs of cell evolution. While the defense program is characterized by activation of the immune response and anabolic metabolism, the dormancy program is an energy-preserving state with high resistance to environmental stressors, and it has strong analogy with animal hibernation where fuel is stored, metabolic rate is suppressed, and insulin secretion is reduced. The metabolic changes that follow treatment with SGLT2i are reminiscent of the metabolic picture characteristic of the dormancy program. Therefore, we hypothesize that the beneficial cardioprotective effects of SGLT2i may be related to their ability to switch cell life programming from a defense to a dormancy state, thus lending additional benefit.

Association Between Severity of Diabetic Neuropathy and Success in Weight Loss During Hospitalization Among Japanese Patients with Type 2 Diabetes: A Retrospective Observational Study

INTRODUCTION

This study aimed to examine the association between severity of diabetic neuropathy and weight loss during hospitalization in overweight participants with type 2 diabetes.

PATIENTS AND METHODS

Participants of this study comprised 193 patients who were hospitalized for type 2 diabetes treatment. The participants were divided into two groups in the study, based on whether or not reduction of bodyweight was at least 3% during hospitalization. Using Cox models, the association between severity of neuropathy and effectiveness of weight loss under a controlled diet was analyzed. Autonomic neuropathy was assessed on patient admission by R-R interval, as measured in an electrocardiogram (CVRR), and sensory neuropathy was assessed using both 128-Hz tuning-fork vibration and Achilles tendon reflex (ATR).

RESULTS

The adjusted hazard ratio for weight loss of at least 3% for CVRR was 1.17 (95% confidence interval 1.07-1.28, P=0.0006) and for vibration time 1.93 (1.01-3.68, P=0.045). After dividing CVRR and vibration time into tertiles based on participant number, the adjusted hazard ratio for the high tertile of CVRR was 2.17 (1.29-3.62, P=0.003), and for the long tertile of vibration time 1.84 (1.10-3.08, P=0.02), compared with the low and short tertiles, respectively. No association was detected between ATR category and weight loss.

CONCLUSION

Severity of diabetic neuropathy was found to be a determinant in weight loss under a caloric restriction regimen for patients with type 2 diabetes. The results of the study suggest that the peripheral nervous system is involved in responses to medical intervention for treatment for type 2 diabetes including bodyweight management.

Dapagliflozin Activates Neurons in the Central Nervous System and Regulates Cardiovascular Activity by Inhibiting SGLT-2 in Mice

PURPOSE

This study investigates the possible effect and central mechanism of novel antidiabetic medication sodium glucose transporter-2 (SGLT-2i) on the cardiovascular activity.

MATERIAL AND METHODS

Thirty-four normal male C57BL/6 mice were randomly assigned to 2 groups to receive single Dapagliflozin (1.52mg/kg) dose via intragastric gavage or a comparable dose of saline. Glycemic level (BG), blood pressure (BP) and heart rate (HR) were measured 2 hours after administration of the respective treatments. Immunohistochemical tests were performed to determine the effect of SGLT-2i on neural localization of SGLT-2 and c-Fos, a neural activator. The distributional relationships of SGLT-2 and c-Fos were examined by immunofluorescence.

RESULTS

Administration of SGLT-2i significantly decreased BP but did not affect the HR. There was no difference in BG between the two groups. Results showed that SGLT-2 was localized to specific regions involved in autonomic control. Expression of c-Fos was significantly higher in major critical nuclei in the aforementioned regions in groups treated with Dapagliflozin.

CONCLUSION

This study demonstrates that SGLT-2 is expressed in CNS tissues involved in autonomic control and possibly influence cardiovascular function. Dapagliflozin influences central autonomic activity via unidentified pathways by inhibiting central or peripheral SGLT-2. These results provide a new concept that sympathetic inhibition by SGLT-2i can be mediated by central autonomic system, a mechanism that explains how SGLT-2i improves the cardiovascular function.

Glucose effectiveness and its components in relation to body mass index

BACKGROUND

Obesity is known to induce a deterioration of insulin sensitivity (S_I ), one of the insulin-dependent components of glucose tolerance. However, few studies investigated whether obesity affects also the insulin-independent component, that is glucose effectiveness (S_G ). This cross-sectional study aimed to analyse S_G and its components in different body mass index (BMI) categories.

MATERIALS AND METHODS

Three groups of subjects spanning different BMI (kg m^-2 ) categories underwent a 3-h frequently sampled intravenous glucose tolerance test: Lean (LE; 18.5 ≤ BMI < 25, n = 73), Overweight (OW; 25 ≤ BMI < 30, n = 90), and Obese (OB; BMI ≥ 30, n = 41). OB has been further divided into two subgroups, namely Obese I (OB-I; 30 ≤ BMI < 35, n = 27) and Morbidly Obese (OB-M; BMI ≥ 35, n = 14). Minimal model analysis provided S_G and its components at zero (GEZI) and at basal (BIE) insulin.

RESULTS

Values for S_G were 1.98 ± 1.30 × 10^-2 ·min^-1 in all subjects grouped and 2.38 ± 1.23, 1.84 ± 0.82, 1.59 ± 0.61 10^-2 ·min^-1 in LE, OW and OB, respectively. In all subjects grouped, a significant inverse linear correlation was found between the log-transformed values of S_G and BMI (r = -0.3, P < 0.0001). S_G was significantly reduced in OW and OB with respect to LE (P < 0.001) but no significant difference was detected between OB and OW (P = 0.35) and between OB-I and OB-M (P = 0.25). Similar results were found for GEZI. BIE was not significantly different among NW, OW and OB (P = 0.11) and between OB-I and OB-M (P ≥ 0.07).

CONCLUSIONS

S_G and its major component GEZI deteriorate in overweight individuals compared to those in the normal BMI range, without further deterioration when BMI increases above 30 kg m^-2 .

Metabolic effects of antidiabetic drugs on adipocytes and adipokine expression

Several classes of antidiabetic agents have been developed that achieve their hypoglycemic outcomes via various molecular mechanisms. Adipose tissue is a major metabolic and energy-storing tissue and plays an important role in many metabolic pathways, including insulin signaling and insulin sensitivity. Adipose tissue monitors and regulates whole body homeostasis via production and release of potent proteins, such as adipokine and adiponectin, into the circulation. Therefore, any agent that can modulate adipocyte metabolism can, in turn, affect metabolic and glucose homeostatic pathways. Antidiabetic drugs are not only recognized primarily as hypoglycemic agents but may also alter adipose tissue itself, as well as adipocyte-derived adipokine expression and secretion. In the current review, we present the major evidence concerning routinely used antidiabetic agents on adipocyte metabolism and adipokine expression.

Metabolic effects of Tofogliflozin are efficiently enhanced with appropriate dietary carbohydrate ratio and are distinct from carbohydrate restriction

Sodium‐glucose cotransporter 2 inhibitors (SGLT2i) exert their antidiabetic effects by promoting urinary glucose excretion. Nutrition therapy is obviously important, but little is known about the interactions between SGLT2i agents and carbohydrate restriction. Therefore, we studied these interactions using an obese diabetic animal model. KK‐A^y mice were pair‐fed normal chow [NC; carbohydrate: fat: protein = 65:15:20], low carbohydrate [LC; 43:42:15] or severely carbohydrate restricted diets [SR; 12:45:43] for 12 weeks. Tofogliflozin (Tofo) was administered as the SGLT2i in the NC and LC diet groups. Blood glucose levels were significantly increased in the SR group. Tofo reduced blood glucose levels significantly in the NC group during the experiment and in the LC group at 2‐6 weeks. Plasma triglycerides were markedly elevated in the SR group without Tofo, but decreased in response to Tofo administration. Hepatic triglyceride contents were not changed by the LC or the SR diet alone. However, Tofo ameliorated hepatosteatosis in NC‐fed animals. Consistent with the downregulation of stearoyl‐CoA desaturase 1, the ratio of plasma monounsaturated to saturated fatty acids was significantly reduced in the LC with Tofo and in the SR alone groups, but was not altered in the NC with Tofo group. In summary, metabolism of glucose and lipids was improved by Tofo but not by the SR diet. Furthermore, Tofo improved these parameters more effectively in the NC than in the LC diet group. These data suggest that the effects of SGLT2i are distinct from those of carbohydrate restriction and that a nonrestricted dietary carbohydrate composition is essential for SGLT2i treatment to be effective.

The actions of SGLT2 inhibitors on metabolism, renal function and blood pressure

Inhibition of the sodium-glucose cotransporter (SGLT) 2 in the proximal tubule of the kidney has a broad range of effects on renal function and plasma volume homeostasis, as well as on adiposity and energy metabolism across the entire body. SGLT2 inhibitors are chiefly used in type 2 diabetes for glucose control, achieving reductions in HbA_1c of 7-10 mmol/mol (0.6-0.9%) when compared with placebo. This glucose-lowering activity is proportional to the ambient glucose concentration and glomerular filtration of this glucose, so may be greater in those with poor glycaemic control and/or hyperfiltration at baseline. Equally, the glucose-lowering effects of SGLT2 inhibitors are attenuated in individuals without diabetes and those with a reduced eGFR. However, unlike the glucose-lowering effects of SGLT2 inhibitors, the spill-over of sodium and glucose beyond the proximal nephron following SGLT2 inhibition triggers dynamic and reversible realignment of energy metabolism, renal filtration and plasma volume without relying on losses into the urine. In addition, these processes are observed in the absence of significant glucosuria or ongoing natriuresis. In the long term, the resetting of energy/salt/water physiology following SGLT2 inhibition has an impact, not only on adiposity, renal function and blood pressure control, but also on the health and survival of patients with type 2 diabetes. A better understanding of the precise biology underlying the acute actions of SGLT2 inhibitors in the kidney and how they are communicated to the rest of the body will likely lead to improved therapeutics that augment similar pathways in individuals with, or even without, diabetes to achieve additional benefits.