SGLT2 inhibitors and the autonomic nervous system in diabetes: A promising challenge to better understand multiple target improvement

Evidence of a bi-directional relationship between heart failure and diabetes: a strategy for the detection of glucose abnormalities and diabetes prevention in patients with heart failure

Prevalence of heart failure (HF) and diabetes are markedly increasing globally. In a population of HF patients, approximately 40% have diabetes which is associated with a more severe HF, poorer cardiovascular outcomes and higher hospitalization rates for HF than HF patients without diabetes. Similar trends were shown in HF patients with prediabetes. In addition, the association between HF and renal function decline was demonstrated in patients with or without diabetes. However, the exact prevalence of dysglycemia in HF patients requires further investigation aiming to clarify the most accurate test to detect dysglycemia in this population. The relationship between HF and diabetes is complex and probably bidirectional. In one way, patients with diabetes have a more than two-fold risk of developing incident HF with reduced or preserved ejection fraction than those without diabetes. In the other way, patients with HF, when compared with those without HF, show an increased risk for the onset of diabetes due to several mechanisms including insulin resistance (IR), which makes HF emerging as a precursor for diabetes development. This article provides epidemiological evidence of undetected dysglycemia (prediabetes or diabetes) in HF patients and reviews the pathophysiological mechanisms which favor the development of IR and the risks associated with these disorders in HF patients. This review also offers a discussion of various strategies for the prevention of diabetes in HF patients, based first on fasting plasma glucose and HbA1c measurement and if normal on an oral glucose tolerance test as diagnostic tools for prediabetes and unknown diabetes that should be performed more extensively in those patients. It discusses the implementation of diabetes prevention measures and well-structured management programs for HF patients who are generally overweight or obese, as well as current pharmacotherapeutic options for prediabetes, including sodium-glucose cotransporter 2 inhibitors which are among the pillars of HF treatment and which recently showed a benefit in the reduction of incident diabetes in HF patients. Thus, there is an urgent need of routine screening for dysglycemia in all HF patients, which should contribute to reduce the incidence of diabetes and to treat earlier diabetes when already present.

Cardiovascular autonomic neuropathy in diabetes: an update with a focus on management

Cardiovascular autonomic neuropathy (CAN) is an under-recognised yet highly prevalent microvascular complication of diabetes. CAN affects approximately 20% of people with diabetes, with recent studies highlighting the presence of CAN in prediabetes (impaired glucose tolerance and/or impaired fasting glucose), indicating early involvement of the autonomic nervous system. Understanding of the pathophysiology of CAN continues to evolve, with emerging evidence supporting a potential link between lipid metabolites, mitochondrial dysfunction and genetics. Recent advancements, such as streamlining CAN detection through wearable devices and monitoring of heart rate variability, present simplified and cost-effective approaches for early CAN detection. Further research on the optimal use of the extensive data provided by such devices is required. Despite the lack of specific pharmacological interventions targeting the underlying pathophysiology of autonomic neuropathy, several studies have suggested a favourable impact of newer glucose-lowering agents, such as sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists, where there is a wealth of clinical trial data on the prevention of cardiovascular events. This review delves into recent developments in the area of CAN, with emphasis on practical guidance to recognise and manage this underdiagnosed condition, which significantly increases the risk of cardiovascular events and mortality in diabetes.

Dapagliflozin Ameliorates Neural Damage in the Heart and Kidney of Diabetic Mice

(1) Background: Measures for the control of diabetes mellitus (DM) and, especially, for the control of its complications represent a main objective of the research carried out on this disease, since both mortality and morbidity relating to DM represent real problems for the health system worldwide. The aim of our study was to evaluate nervous tissue from the heart and kidneys of mice with diabetes induced by streptozotocin (STZ) in the presence or absence of dapagliflozin (DAPA) treatment. (2) Methods: For this purpose, we used 24 C 57Bl/6 male mice, aged between 8 and 10 weeks. The mice were divided into three groups: sham (DM-), control (DM+), and treated (DM+). Diabetes mellitus was induced by injecting a single intraperitoneal dose of STZ. The duration of diabetes in the mice included in our study was 12 weeks after STZ administration; then, the heart and kidneys were sampled, and nervous tissue (using the primary antibody PGP 9.5) from the whole heart, from the atrioventricular node, and from the kidneys was analyzed. (3) Results: The density of nerve tissue registered a significant decrease in animals from the control group (DM+), to a value of 0.0122 ± 0.005 mm2 nerve tissue/mm2 cardiac tissue, compared with the sham group (DM-), wherein the value was 0.022 ± 0.006 mm2 nervous tissue/mm2 cardiac tissue (p = 0.004). Treatment with dapagliflozin reduced the nerve tissue damage in the treated (DM+DAPA) group of animals, resulting in a nerve tissue density of 0.019 ± 0.004 mm2 nerve tissue/mm2 cardiac tissue; a statistically significant difference was noted between the control (DM+) and treated (DM+DAPA) groups (p = 0.046). The same trends of improvement in nerve fiber damage in DM after treatment with DAPA were observed both in the atrioventricular node and in the kidneys. (4) Conclusions. These data suggest that dapagliflozin, when used in streptozotocin-induced diabetes in mice, reduces the alteration of the nervous system in the kidneys and in the heart, thus highlighting better preservation of cardiac and renal homeostasis, independent of any reduction in the effects of hyperglycemia produced in this disease.

A Nonrandomized Trial of the Effects of Passive Simulated Jogging on Short-Term Heart Rate Variability in Type 2 Diabetic Subjects

Background

Diabetes mellitus has reached global epidemic proportions, with type 2 diabetes (T2DM) comprising more than 90% of all subjects with diabetes. Cardiovascular autonomic neuropathy (CAN) frequently occurs in T2DM. Heart rate variability (HRV) reflects a neural balance between the sympathetic and parasympathetic autonomic nervous systems (ANS) and a marker of CAN. Reduced HRV has been shown in T2DM and improved by physical activity and exercise. External addition of pulses to the circulation, as accomplished by a passive simulated jogging device (JD), restores HRV in nondiseased sedentary subjects after a single session. We hypothesized that application of JD for a longer period (7 days) might improve HRV in T2DM participants.

Methods

We performed a nonrandomized study on ten T2DM subjects (age range 44-73 yrs) who were recruited and asked to use a physical activity intervention, a passive simulated jogging device (JD) for 7 days. JD moves the feet in a repetitive and alternating manner; the upward movement of the pedal is followed by a downward movement of the forefoot tapping against a semirigid bumper to simulate the tapping of feet against the ground during jogging. Heart rate variability (HRV) analysis was performed using an electrocardiogram in each subject in seated posture on day 1 (baseline, BL), after seven days of JD (JD7), and seven days after discontinuation of JD (Post-JD). Time domain variables were computed, viz., standard deviation of all normal RR intervals (SDNN), standard deviation of the delta of all RR intervals (SDΔNN), and the square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD). Frequency domain measures were determined using a standard Fast Fourier spectral analysis, as well as the parameters of the Poincaré plots (SD1 and SD2).

Results

Seven days of JD significantly increased SDNN, SDΔNN, RMSSD, and both SD1 and SD2 from baseline values. The latter parameters remained increased Post-JD. JD did not modify the frequency domain measures of HRV.

Conclusion

A passive simulated jogging device increased the time domain and Poincaré variables of HRV in T2DM. This intervention provided effortless physical activity as a novel method to harness the beneficial effects of passive physical activity for improving HRV in T2DM subjects.

Diabetes-Induced Cardiac Autonomic Neuropathy: Impact on Heart Function and Prognosis

Cardiovascular autonomic neuropathy (CAN) is a severe complication of the advance stage of diabetes. More than 50% of diabetic patients diagnosed with peripheral neuropathy will have CAN, with clinical manifestations including tachycardia, severe orthostatic hypotension, syncope, and physical exercise intolerance. Since the prevalence of diabetes is increasing, a concomitant increase in CAN is expected and will reduce quality of life and increase mortality. Autonomic dysfunction is associated with reduced baroreflex sensitivity and impairment of sympathetic and parasympathetic modulation. Various autonomic function tests are used to diagnose CAN, a condition without adequate treatment. It is important to consider the control of glucose level and blood pressure as key factors for preventing CAN progression. However, altered biomarkers of inflammatory and endothelial function, increased purinergic receptor expression, and exacerbated oxidative stress lead to possible targets for the treatment of CAN. The present review describes the molecular alterations seen in CAN, diagnosis, and possible alternative treatments.

Baroreceptor Sensitivity in Individuals with CKD and Heart Failure

Background

Heart failure is the most common cardiovascular complication of chronic kidney disease (CKD) and foreshadows a high morbidity and mortality rate. Baroreflex impairment likely contributes to cardiovascular mortality. We aimed to study the associations between CKD, heart failure, and baroreflex sensitivity (BRS) and their association with cardiovascular outcomes.

Methods

We retrospectively analyzed data from a cohort of 247 individuals with moderate to severe HF. All subjects underwent BRS measurements after intravenous phenylephrine along with electrocardiography, echocardiography, and laboratory measurements. We used logistic regression models to assess the association of CKD (estimated glomerular filtration rate <60 ml/min per 1.73 m²) with BRS using iterative models. Cox proportional hazards models were used to assess associations of binary BRS and subgroups according to categorizations of CKD and BRS with cardiovascular mortality.

Results

Median eGFR among individuals with CKD was 52 (IQR 44-56) ml/min per 1.73 m². eGFR was lower in those with depressed BRS (65 [IQR 54-76] ml/min per 1.73 m²) compared with those with preserved BRS (73 [IQR 64-87] ml/min per 1.73 m²; P≤0.001). The majority of individuals with CKD had depressed BRS compared with those without CKD (60% versus 29%; P=0.05). In regression models, CKD and BRS were independently associated. Cardiovascular mortality was significantly increased in individuals with or without CKD and depressed BRS compared with those with preserved BRS and CKD.

Conclusions

Cardiac BRS is depressed in patients with mild to moderate CKD and HF and associated with cardiovascular mortality. Additional study to confirm its contribution to cardiovascular mortality, particularly in advanced CKD, is warranted.

Pathophysiological and clinical aspects of the circadian rhythm of arterial stiffness in diabetes mellitus: A minireview

Several cross-sectional trials have revealed increased arterial stiffness connected with the cardiac autonomic neuropathy in types 2 and 1 diabetic patients. The pathophysiological relationship between arterial stiffness and autonomic dysfunction in diabetes mellitus is still underinvestigated and the question whether the presence of cardiac autonomic neuropathy leads to arterial stiffening or increased arterial stiffness induced autonomic nervous system impairment is still open. Both arterial stiffness and dysfunction of the autonomic nervous system have common pathogenetic pathways, counting state of the chronic hyperinsulinemia and hyperglycemia, increased formation of advanced glycation end products, activation of protein kinase C, development of endothelial dysfunction, and chronic low-grade inflammation. Baroreceptor dysfunction is thought to be one of the possible reasons for the arterial wall stiffening development and progression. On the contrary, violated autonomic nervous system function can affect the vascular tone and by this way alter the large arteries walls elastic properties. Another possible mechanism of attachment and/or development of arterial stiffness is the increased heart rate and autonomic dysfunction corresponding progression. This minireview analyzes the current state of the relationship between the diabetes mellitus and the arterial stiffness. Particular attention is paid to the analysis, interpretation, and application of the results obtained in patients with type 2 diabetes mellitus and diabetic cardiac autonomic neuropathy.

Neuroprotective effects of Canagliflozin: Lessons from aged genetically diverse UM-HET3 mice

The aging brain is characterized by progressive increases in neuroinflammation and central insulin resistance, which contribute to neurodegenerative diseases and cognitive impairment. Recently, the Interventions Testing Program demonstrated that the anti-diabetes drug, Canagliflozin (Cana), a sodium-glucose transporter 2 inhibitor, led to lower fasting glucose and improved glucose tolerance in both sexes, but extended median lifespan by 14% in male mice only. Here, we show that Cana treatment significantly improved central insulin sensitivity in the hypothalamus and the hippocampus of 30-month-old male mice. Aged males produce more robust neuroimmune responses than aged females. Remarkably, Cana-treated male and female mice showed significant reductions in age-associated hypothalamic gliosis with a decrease in inflammatory cytokine production by microglia. However, in the hippocampus, Cana reduced microgliosis and astrogliosis in males, but not in female mice. The decrease in microgliosis was partially correlated with reduced phosphorylation of S6 kinase in microglia of Cana-treated aged male, but not female mice. Thus, Cana treatment improved insulin responsiveness in aged male mice. Furthermore, Cana treatment improved exploratory and locomotor activity of 30-month-old male but not female mice. Taken together, we demonstrate the sex-specific neuroprotective effects of Cana treatment, suggesting its application for the potential treatment of neurodegenerative diseases.

Diagnostic Tools, Biomarkers, and Treatments in Diabetic polyneuropathy and Cardiovascular Autonomic Neuropathy

The various manifestations of diabetic neuropathy, including distal symmetric sensorimotor polyneuropathy (DSPN) and cardiovascular autonomic neuropathy (CAN), are among the most prevalent chronic complications of diabetes. Major clinical complications of diabetic neuropathies, such as neuropathic pain, chronic foot ulcers, and orthostatic hypotension, are associated with considerable morbidity, increased mortality, and diminished quality of life. Despite the substantial individual and socioeconomic burden, the strategies to diagnose and treat diabetic neuropathies remain insufficient. This review provides an overview of the current clinical aspects and recent advances in exploring local and systemic biomarkers of both DSPN and CAN assessed in human studies (such as biomarkers of inflammation and oxidative stress) for better understanding of the underlying pathophysiology and for improving early detection. Current therapeutic options for DSPN are (I) causal treatment, including lifestyle modification, optimal glycemic control, and multifactorial risk intervention, (II) pharmacotherapy derived from pathogenetic concepts, and (III) analgesic treatment against neuropathic pain. Recent advances in each category are discussed, including non-pharmacological approaches, such as electrical stimulation. Finally, the current therapeutic options for cardiovascular autonomic complications are provided. These insights should contribute to a broader understanding of the various manifestations of diabetic neuropathies from both the research and clinical perspectives.

SGLT2 Inhibition by Dapagliflozin Attenuates Diabetic Ketoacidosis in Mice with Type-1 Diabetes

BACKGROUND

SGLT2 inhibitors increase plasma ketone concentrations. It has been suggested that insulinopenia, along with an increase in the counter-regulatory hormones epinephrine, corticosterone, glucagon and growth hormone, can induce ketoacidosis, especially in type-1 diabetes (T1DM). Dehydration precipitates SGLT2 inhibitor-induced ketoacidosis in type-2 diabetes. We studied the effects of dapagliflozin and water deprivation on the development of ketoacidosis and the associated signaling pathways in T1DM mice.

METHODS

C57BL/6 mice were fed a high-fat diet. After 7 days, some mice received intraperitoneal injection of streptozocin + alloxan (STZ/ALX). The treatment groups were control + water at lib; control + dapagloflozin + water at lib; control + dapagloflozin + water deprivation; STZ/ALX + water at lib; STZ/ALX + water deprivation; STZ/ALX + dapagloflozin + water at lib; STZ/ALX + dapagloflozin + water deprivation. Dapagliflozin was given for 7 days. In the morning of day 18, food was removed, and water was removed in the water deprivation groups. ELISA, rt-PCR, and immunoblotting were used to assess blood, heart, liver, white and brown adipose tissues.

RESULTS

The T1DM mice had ketoacidosis even without water deprivation. Water deprivation increased plasma levels of β-hydroxybutyrate, acetoacetate, corticosterone, and epinephrine and reduced the levels of adiponectin in T1DM mice. Interleukin (IL) 1β, IL-6, IL-8, and TNFα were also increased in the T1DM mice with water deprivation. Dapagliflozin attenuated the changes in the T1DM mice without and with water deprivation. Likewise, water deprivation increased the activation of the inflammasome in the heart, liver, and white fat of the T1DM mice and dapagliflozin attenuated these changes. Dapagliflozin reduced the mRNA levels of glucagon receptors in the liver and the increase in GPR109a in white and brown fat. In the liver, dapagliflozin increased AMPK phosphorylation, and attenuated the phosphorylation of TBK1 and the activation of NFκB.

CONCLUSIONS

Dapagliflozin reduced ketone body levels and attenuated the activation of NFκB and the activation of the inflammasome in T1DM mice with ketoacidosis.

Possible Preventative/Rehabilitative Role of Gliflozins in OSA and T2DM. A Systematic Literature Review-Based Hypothesis

Obstructive sleep apnoea (OSA) is characterized by frequent apnoea episodes during sleep due to upper airway obstruction. The present review summarizes current knowledge on inter-relationships between OSA and type 2 diabetes mellitus (T2DM) and suggests the former as a possible target for sodium-glucose co-transporter-2 inhibitors (SGLT-2i). Based on pathophysiological mechanisms underlying OSA onset and renal SGLT-2 effects, we suggest that SGLT-2i indications might expand beyond current ones, including glucose, lipids, uric acid, blood pressure, and body weight control as well as chronic heart failure and kidney disease prevention.

The impact of diabetes on heart failure development: The cardio-renal-metabolic connection

Heart failure (HF) and chronic kidney disease (CKD) are often associated in type 2 diabetes (T2D), aggravate each other and exert synergistic effects to increase the risk of cardiac and renal events. The risks of renal worsening in HF patients and HF in CKD patients need to be evaluated to tailor preventive therapy. The recent CV and renal trials enriched our knowledge about the natural history of HF and CKD in T2D and provided evidence for the benefit of sodium-glucose cotransporter 2 inhibitors (SGLT2is) in HF and renal decline prevention. SGLT-2is are the best choice in patients with HFrEF to improve CV prognosis and HF-related outcomes and also to prevent kidney-related outcomes, and in CKD patients to slow down renal failure and also reduce hospitalization for HF and CV death. In both situations the number of patients to treat in order to prevent such events in one patient is lower than in the general T2D population at high CV risk. GLP1-receptor agonists could be an alternative in a patient who is intolerant or has a contraindication to SGLT-2is. A tight collaboration between diabetologists, nephrologists and cardiologists should be encouraged for a holistic and effective strategy to reduce the burden of cardio-renal-metabolic interaction.

SGLT2 inhibitors and lower limb complications: an updated meta-analysis

Background

To exam the associations between the use of sodium glucose co-transporter 2 inhibitor (SGLT2i) and the risk of lower limb complications, and to analyze the associated factors.

Methods

Pubmed, Medline, Embase, the Cochrane Center Register of Controlled Trials for Studies and Clinicaltrial.gov were searched from the inception to November 2020. Randomized controlled trials of SGLT2i conducted in population containing diabetic patients with reports of amputation, peripheral arterial disease (PAD) and diabetic foot (DF) events were included. Random-effect model, fixed-effect model and meta-regression analysis were accordingly used.

Result

The numbers of SGLT2i users versus non-SGLT2i users in the analyses of amputation, PAD and DF were 40,925/33,414, 36,446/28,685 and 31,907/25,570 respectively. Compared with non-SGLT2i users, the risks of amputation and PAD were slightly increased in patients with canagliflozin treatment (amputation: OR = 1.60, 95% CI 1.04 to 2.46; PAD: OR = 1.53, 95 % CI 1.14 to 2.05). Meta-regression analyses indicated that greater weight reduction in SGLT2i users was significantly associated with the increased risks of amputation (β = − 0.461, 95% CI − 0.726 to − 0.197), PAD (β = − 0.359, 95% CI − 0.545 to − 0.172) and DF (β = − 0.476, 95% CI − 0.836 to − 0.116). Lower baseline diastolic blood pressure (β = − 0.528, 95% CI − 0.852 to − 0.205), more systolic blood pressure reduction (β = − 0.207, 95% CI − 0.390 to − 0.023) and more diastolic blood pressure reduction (β = − 0.312, 95% CI − 0.610 to − 0.015) were significantly associated with the increased risks of amputation, PAD and DF respectively in patients with SGLT2i treatment.

Conclusions

The risks of amputation and PAD were slightly increased in patients with canagliflozin treatment. Reductions in body weight and blood pressure were associated with lower limb complications in patients with SGLT2i treatment.