Glucose toxicity: the leading actor in the pathogenesis and clinical history of type 2 diabetes - mechanisms and potentials for treatment

Spontaneous remission and relapse of diabetes mellitus in a male dog

An 8-year-old male neutered Miniature Schnauzer was diagnosed with diabetes mellitus based on fasting hyperglycemia and glucosuria after a 2-week history of polydipsia and periuria, in line with the Agreeing Language in Veterinary Endocrinology consensus definition. Treatment of insulin and dietary management was initiated. The insulin dose was gradually reduced and eventually discontinued over the next year based on spot blood glucose concentrations that revealed euglycemia or hypoglycemia. After discontinuation, the dog remained free of clinical signs for 1 year until it was again presented for polyuria/polydipsia with fasting hyperglycemia and glucosuria. Insulin therapy was resumed and continued for the remainder of the dog's life. Although diabetic remission often occurs in cats and humans, the presumed etiopathogenesis of pancreatic beta cell loss makes remission rare in dogs, except for cases occurring with diestrus or pregnancy. This case demonstrates that diabetic remission is possible in dogs, even in cases without an identifiable reversible trigger.

Labial Necrotizing Fasciitis Caused by Pelvic Eggerthia catenaformis Infection

A patient with comorbid diabetes mellitus, obesity, and hypertension acutely presented to the ED due to labial cellulitis with rapidly progressing symptoms of systemic inflammation. Clinical examination revealed fever and groin pain that was tender to palpation. Initial contrast-enhanced CT scans showed labial cellulitis extending to the inguinal canal, with later CT imaging findings of subcutaneous air indicative of necrotizing fasciitis (NF). Antimicrobial therapy was initiated empirically and later tailored to culture antibiogram. The patient underwent acute surgical abscess drainage and tissue debridement but was transferred to the surgical intensive care unit (SICU) due to postoperative blood loss and hypotension. Two additional surgical procedures were needed before sufficient drainage was achieved, and Eggerthia catenaformis (E. catenaformis) was isolated from all samples. Due to the extent of the infection, the patient was admitted for a total of 16 days, with five days spent in the SICU. They recovered completely due to adequate surgery and antimicrobial therapy for a total of 24 days. Here, we present the third reported case of NF due to E. catenaformiswhile emphasizing timely treatment with empiric antibiotics and surgical intervention.

Biomarkers of Oxidative Stress in Diabetes Mellitus with Diabetic Nephropathy Complications

The present study aimed to investigate and compare biomarkers of oxidative stress and the activity of antioxidant enzymes in the plasma of patients with different stages of diabetic nephropathy. For this purpose, we studied (1) the levels of reactive oxygen species and reactive nitrogen species as oxidative stress parameters, (2) lipid and protein oxidation, (3) the activity of antioxidant enzymes, and (4) cytokine production. Patients with type 2 diabetes mellitus were divided into three groups according to the loss of renal function: patients with compensated diabetes mellitus with normal renal function DMT2N0 measured as an estimated glomerular filtration rate (eGFR) ≥ 90 mL/min/1.73 m2, a group with decompensated diabetes mellitus with complication diabetic nephropathy and mild-to-moderate loss of renal function DMT2N1 (eGFR < 60 mL/min/1.73 m2: 59-45 mL/min/1.73 m2), and a decompensated diabetes mellitus with diabetic nephropathy group with moderate-to-severe loss of renal function DMT2N2 (eGFR > 30 mL/min/1.73 m2: 30-44 mL/min/1.73 m2). All results were compared with healthy volunteers. The results showed that patients with diabetic nephropathy had significantly higher levels of ROS, cytokine production, and end products of lipid and protein oxidation compared to healthy volunteers. Furthermore, patients with diabetic nephropathy had depleted levels of nitric oxide (NO), an impaired NO synthase (NOS) system, and reduced antioxidant enzyme activity (p < 0.05). These findings suggest that patients with impaired renal function are unable to compensate for oxidative stress. The decreased levels of NO radicals in patients with advanced renal complications may be attributed to damage NO availability in plasma. The study highlights the compromised oxidative status as a contributing factor to impaired renal function in patients with decompensated type 2 diabetes mellitus. The findings of this study have implications for understanding the pathogenesis of diabetic nephropathy and the role of oxidative stress and chronic inflammation in its development. The assessment of oxidative stress levels and inflammatory biomarkers may aid in the early detection and prediction of diabetic complications.

Necrotizing fasciitis in Indonesian adult with diabetes mellitus: Two case and review article

Background

Necrotizing fasciitis (NF) is a rare and life-threatening form of infection involving rapidly spreading inflammation and extensive necrosis of the skin, subcutaneous tissue, and superficial fascia.

Case presentation

This study reported two cases of NF in a 56-year-old female and a 38-year-old male who demonstrated typical signs and symptoms of NF. Both presented to the hospital with skin necrosis in the lower extremity, sepsis shock, and multiorgan failure. Based on the clinical presentation, physical examination, and additional examination, a diagnosis of NF was made. The LRINEC score was used to distinguish NF from other soft tissue infections. Both patients were treated with empirical antibiotics, surgical debridement and planned to be amputated, but the patients were hemodynamically unstable and passed away before the amputation proceeded.

Discussion

Delay in the diagnosis of NF increases the risk of mortality and the use of the LRINEC score is very helpful in decision making for health workers.

Conclusion

The key to the management of NF is early diagnosis, debridement, removal of necrotic tissue, amputation, and use of empirical antibiotics.

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Early diagnosis of necrotizing fasciitis (NF) is key in the management of the disease.

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The diagnosis of NF is established using the LRINEC score.

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Debridement and amputation play an important role in preventing the spread of microorganisms in NF.

Factors Affecting Patients with Concurrent Deep Neck Infection and Cervical Necrotizing Fasciitis

Deep neck infection (DNI) is a severe disease of the deep neck spaces, which has the potential for airway obstruction. Cervical necrotizing fasciitis (CNF) is a fatal infection of the diffuse soft tissues and fascia with a high mortality rate. This study investigated risk factors in patients with concurrent DNI and CNF. A total of 556 patients with DNI were included in this study between August 2016 and December 2021. Among these patients, 31 had concurrent DNI and CNF. The relevant clinical variables were assessed. In univariate analysis, age (> 60 years, odds ratio (OR) = 2.491, p = 0.014), C-reactive protein (CRP, OR = 1.007, p < 0.001), blood sugar (OR = 1.007, p < 0.001), and diabetes mellitus (DM, OR = 4.017, p < 0.001) were significant risk factors for concurrent DNI and CNF. In multivariate analysis, CRP (OR = 1.006, p < 0.001) and blood sugar (OR = 1.006, p = 0.002) were independent risk factors in patients with concurrent DNI and CNF. There were significant differences in the length of hospital stay and therapeutic management (intubation, tracheostomy, incision and drainage) between DNI patients with and without CNF (all p < 0.05). While there were no differences in pathogens between the DNI alone and concurrent DNI and CNF groups (all p > 0.05), the rate of specific pathogen non-growth from blood cultures was 16.95% (89/525) in the DNI alone group, in contrast to 0% (0/31) in the concurrent DNI and CNF group (p = 0.008). Higher CRP and blood sugar levels were independent risk factors for the concurrence of DNI and CNF. With regard to prognosis, there were significant differences in the length of hospital stay and therapeutic management between the groups with and without CNF. While there were no significant differences in pathogens (all p > 0.05), no cases in the concurrent DNI and CNF group showed specific pathogen non-growth, in contrast to 89/525 patients in the group with DNI alone.

Lessons from bariatric surgery: Can increased GLP-1 enhance vascular repair during cardiometabolic-based chronic disease?

Type 2 diabetes (T2D) and obesity represent entangled pandemics that accelerate the development of cardiovascular disease (CVD). Given the immense burden of CVD in society, non-invasive prevention and treatment strategies to promote cardiovascular health are desperately needed. During T2D and obesity, chronic dysglycemia and abnormal adiposity result in systemic oxidative stress and inflammation that deplete the vascular regenerative cell reservoir in the bone marrow that impairs blood vessel repair and exacerbates the penetrance of CVD co-morbidities. This novel translational paradigm, termed 'regenerative cell exhaustion' (RCE), can be detected as the depletion and dysfunction of hematopoietic and endothelial progenitor cell lineages in the peripheral blood of individuals with established T2D and/or obesity. The reversal of vascular RCE has been observed after administration of the sodium-glucose cotransporter-2 inhibitor (SGLT2i), empagliflozin, or after bariatric surgery for severe obesity. In this review, we explore emerging evidence that links improved dysglycemia to a reduction in systemic oxidative stress and recovery of circulating pro-vascular progenitor cell content required for blood vessel repair. Given that bariatric surgery consistently increases systemic glucagon-like-peptide 1 (GLP-1) release, we also focus on evidence that the use of GLP-1 receptor agonists (GLP-1RA) during obesity may act to inhibit the progression of systemic dysglycemia and adiposity, and indirectly reduce inflammation and oxidative stress, thereby limiting the impact of RCE. Therefore, therapeutic intervention with currently-available GLP-1RA may provide a less-invasive modality to reverse RCE, bolster vascular repair mechanisms, and improve cardiometabolic risk in individuals living with T2D and obesity.

Psidium guajava L. leaf extract inhibits adipocyte differentiation and improves insulin sensitivity in 3T3-L1 cells

BACKGROUND/OBJECTIVES

Psidium guajava L. (guava) leaves have been shown to exhibit hypoglycemic and antidiabetic effects in rodents. This study investigated the effects of guava leaf extract on adipogenesis, glucose uptake, and lipolysis of adipocytes to examine whether the antidiabetic properties are mediated through direct effects on adipocytes.

MATERIALS/METHODS

3T3-L1 cells were treated with 25, 50, 100 µg/mL of methanol extract from guava leaf extract (GLE) or 0.1% dimethyl sulfoxide as a control. Lipid accumulation was evaluated with Oil Red O Staining and AdipoRed assay. Immunoblotting was performed to measure the expression of adipogenic transcription factors, fatty acid synthase (FAS), and AMP-activated protein kinase (AMPK). Glucose uptake under basal or insulin-stimulated condition was measured using a glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose. Lipolysis from fully differentiated adipocytes was measured by free fatty acids release into the culture medium in the presence or absence of epinephrine.

RESULTS

Oil Red O staining and AdipoRed assay have shown that GLE treatment reduced lipid accumulation during adipocyte differentiation. Mitotic clonal expansion, an early essential event for adipocyte differentiation, was inhibited by GLE treatment. GLE inhibited the expression of transcription factors involved in adipocyte differentiation, such as peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein-1c (SREBP-1c). FAS expression was also decreased while the phosphorylation of AMPK was increased by GLE treatment. In addition, GLE increased insulin-induced glucose uptake into adipocytes. In lipid-filled mature adipocytes, GLE enhanced epinephrine-induced lipolysis but reduced basal lipolysis dose-dependently.

CONCLUSIONS

The results show that GLE inhibits adipogenesis and improves adipocyte function by reducing basal lipolysis and increasing insulin-stimulated glucose uptake in adipocytes, which can be partly associated with antidiabetic effects of guava leaves.

Prediabetes: how pathophysiology drives potential intervention on a subclinical disease with feared clinical consequences

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder whose rising incidence suggests the epidemic proportions of the disease. Impaired Fasting Glucose (IFG) and Impaired Glucose Tolerance (IGT) - alone or combined - represent two intermediate metabolic condition between Normal Glucose Tolerance (NGT) and overt T2DM. Several studies have demonstrated that insulin resistance and beta-cell impairment can be identified even in normoglycemic prediabetic individuals. Worsening of these two conditions may lead to progression of IGT and/or IFG status to overt diabetes. Starting from these assumptions, it seems logical to suppose that interventions aimed at improving metabolic conditions, even in prediabetes, could represent an effective target to halt transition from IGT/IFG to manifest T2DM. Starting from pathophysiological knowledge, in this review we evaluate two possible interventions (lifestyle modifications and pharmacological agents) eligible as prediabetes therapy since they have been demonstrated to improve insulin resistance and beta-cell impairment. Detecting high-risk people and treating them could represent an effective strategy to slow down progression to overt diabetes, normalize glucose tolerance, and even prevent micro- and macrovascular complications.

The Role of the Effects of Endoplasmic Reticulum Stress on NLRP3 Inflammasome in Diabetes

Endoplasmic reticulum (ER) is an important organelle for the protein synthesis, modification, folding, assembly, and the transport of new peptide chains. When the folding ability of ER proteins is impaired, the accumulation of unfolded or misfolded proteins in ER leads to endoplasmic reticulum stress (ERS). The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome, can induce the maturation and secretion of interleukin-1beta (IL-1β) and IL-18 through activating caspase-1. It is associated with many diseases. Studies have shown that ERS can regulate NLRP3 inflammasome in many diseases including diabetes. However, the mechanism of the effects of ERS on NLRP3 inflammasome in diabetes has not been fully understood. This review summarizes the recent researches about the effects of ERS on NLRP3 inflammasome and the related mechanism in diabetes to provide ideas for the relevant basic research in the future.

Overexpression of glucose 6 phosphate dehydrogenase preserves mouse pancreatic beta cells function until late in life

NAD(P)H donates electrons for reductive biosynthesis and antioxidant defense across all forms of life. Glucose-6-phosphate dehydrogenase (G6PD) is a critical enzyme to provide NADPH. G6PD deficiency is present in more than 400 million people worldwide. This enzymopathy provides protection against malaria but sensitizes cells to oxidative stressors. Oxidative stress has been involved in the pathogenesis of the diabetic complications and several studies have provided evidences of a link between G6PD deficiency and type 2 diabetes (T2D). We hypothesized that a moderate overexpression of G6PD (G6PD-Tg) could protect β-cells from age-associated oxidative stress thus reducing the risk of developing T2D. Here we report, that G6PD-Tg mice show an improved glucose tolerance and insulin sensitivity when compared to old age-matched Wild Type (WT) ones. This is accompanied by a decrease in oxidative damage and stress markers in the pancreas of the old Tg animals (20-24month-old). Pancreatic β-cells progress physiologically towards a state of reduced responsiveness to glucose. In pancreatic islets isolated from G6PD-Tg and WT animals at different ages, and using electrophysiological techniques, we demonstrate a wider range of response to glucose in the G6PD-Tg cells that may explain the improvements in glucose tolerance and insulin sensitivity. Together, our results show that overexpression of G6PD maintains pancreatic β-cells from old mice in a "juvenile-like" state and points to the G6PD dependent generation of NADPH as an important factor to improve the natural history of diabetes.

Biliopancreatic Diversion Induces Greater Metabolic Improvement Than Roux-en-Y Gastric Bypass

Diabetes remission is greater after biliopancreatic diversion (BPD) than Roux-en-Y gastric bypass (RYGB) surgery. We used a mixed-meal test with ingested and infused glucose tracers and the hyperinsulinemic-euglycemic clamp procedure with glucose tracer infusion to assess the effect of 20% weight loss induced by either RYGB or BPD on glucoregulation in people with obesity (ClinicalTrials.gov number: NCT03111953). The rate of appearance of ingested glucose into the circulation was much slower, and the postprandial increases in plasma glucose and insulin concentrations were markedly blunted after BPD compared to after RYGB. Insulin sensitivity, assessed as glucose disposal rate during insulin infusion, was ∼45% greater after BPD than RYGB, whereas β cell function was not different between groups. These results demonstrate that compared with matched-percentage weight loss induced by RYGB, BPD has unique beneficial effects on glycemic control, manifested by slower postprandial glucose absorption, blunted postprandial plasma glucose and insulin excursions, and greater improvement in insulin sensitivity.

Sodium-glucose co-transporter inhibitors: Medications that mimic fasting for cardiovascular prevention

Recent evidence that some diabetes drugs can prevent cardiovascular disease (CVD) has profoundly modified the treatment approach to type 2 diabetes mellitus. Sodium-glucose co-transporter-2 (SGLT2) inhibitors and almost all glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been shown, beyond their effect on glucose control, to lead to a significant decrease in the cardiovascular burden of diabetes. Although these results are well known, the mechanisms of action by which they prevent cardiovascular events are still poorly understood. Both GLP-1RAs and SGLT2 inhibitors promote weight loss, although through different mechanisms. SGLT2 inhibitors promote glycosuria, leading to significant caloric deficit and weight loss. Similarly, GLP-1RAs, probably through an anorexic effect on certain brain areas, inhibit calorie intake, with ensuing weight loss. Although it features less prominently in current treatment pathways, pioglitazone has also demonstrated cardiovascular benefits. Pioglitazone profoundly modifies several mechanisms and risk factors responsible for CVD; however, these mechanisms certainly do not include weight loss. Obesity, and consequent insulin resistance, are well known risk factors for CVD, and it would appear logical to attribute the positive cardiovascular effects of these two classes of drugs to weight loss. The direct metabolic effects of these two classes, however, are profoundly different. The present review proposes a unifying hypothesis to explain the reduction in CVD through three different mechanisms of curbing free fatty acid excess, all leading to the common mechanism of cellular caloric restriction. If this hypothesis is correct, the excellent results obtained with SGLT2 inhibitors could be attributed to their close simulation of fasting.

Fucoidan from Undaria pinnatifida has anti-diabetic effects by stimulation of glucose uptake and reduction of basal lipolysis in 3T3-L1 adipocytes

Fucoidan, a sulfated polysaccharide derived from brown seaweeds, has been shown to reduce blood glucose levels and improve insulin sensitivity in mice. We investigated the effects of fucoidan on lipid accumulation, lipolysis, and glucose uptake in 3T3-L1 cells to test the hypothesis that fucoidan exerts an anti-diabetic function by acting directly on adipocytes. The 3T3-L1 cells were treated with 10, 50, 100, and 200 μg/mL of fucoidan from Undaria pinnatifida. Oil Red O staining and AdipoRed assay were used to determine lipid accumulation during adipocyte differentiation. Fucoidan was shown to reduce lipid accumulation and glycerol-3-phosphate dehydrogenase (GPDH) activity in a dose-dependent manner (P < .01). The expression of peroxisome proliferator-activated receptor γ (PPARγ), a major transcription factor associated with adipocyte differentiation, was also suppressed upon treatment with fucoidan. Treatment with fucoidan stimulated glucose uptake in normal adipocytes and restored insulin-stimulated glucose uptake in obesity-induced insulin resistant adipocytes, which were made by incubating hypertrophied 3T3-L1 cells with the conditioned media of RAW 264.7 macrophages (RAW-CM) (P < .01). In the presence of RAW-CM, fucoidan enhanced epinephrine-stimulated lipolysis but reduced basal lipolysis, as determined by non-esterified fatty acid into the culture medium (P < .001). These results suggest that fucoidan may have anti-diabetic effects by improving insulin-stimulated glucose uptake and inhibiting basal lipolysis in adipocytes without inducing adipogenesis.

Empagliflozin Treatment Is Associated With Improved β-Cell Function in Type 2 Diabetes Mellitus

OBJECTIVE

To examine whether lowering plasma glucose concentration with the sodium-glucose transporter-2 inhibitor empagliflozin improves β-cell function in patients with type 2 diabetes mellitus (T2DM).

METHODS

Patients with T2DM (N = 15) received empagliflozin (25 mg/d) for 2 weeks. β-Cell function was measured with a nine-step hyperglycemic clamp (each step, 40 mg/dL) before and at 48 hours and at 14 days after initiating empagliflozin.

RESULTS

Glucosuria was recorded on days 1 and 14 [mean ± standard error of the mean (SEM), 101 ± 10 g and 117 ± 11 g, respectively] after initiating empagliflozin, as were reductions in fasting plasma glucose levels (25 ± 6 mg/dL and 38 ± 8 mg/dL, respectively; both P < 0.05). After initiating empagliflozin and during the stepped hyperglycemic clamp, the incremental area under the plasma C-peptide concentration curve increased by 48% ± 12% at 48 hours and 61% ± 10% at 14 days (both P < 0.01); glucose infusion rate increased by 15% on day 3 and 16% on day 14, compared with baseline (both P < 0.05); and β-cell function, measured with the insulin secretion/insulin resistance index, increased by 73% ± 21% at 48 hours and 112% ± 20% at 14 days (both P < 0.01). β-cell glucose sensitivity during the hyperglycemic clamp was enhanced by 42% at 14 hours and 54% at 14 days after initiating empagliflozin (both P < 0.01).

CONCLUSION

Lowering the plasma glucose concentration with empagliflozin in patients with T2DM augmented β-cell glucose sensitivity and improved β-cell function.

Current advanced therapy cell-based medicinal products for type-1-diabetes treatment

In the XXI century diabetes mellitus has become one of the main threats to human health with higher incidence in regions such as Europe and North America. Type 1 diabetes mellitus (T1DM) occurs as a consequence of the immune-mediated destruction of insulin producing β-cells located in the endocrine part of the pancreas, the islets of Langerhans. The administration of exogenous insulin through daily injections is the most prominent treatment for T1DM but its administration is frequently associated to failure in glucose metabolism control, finally leading to hyperglycemia episodes. Other approaches have been developed in the past decades, such as whole pancreas and islet allotransplantation, but they are restricted to patients who exhibit frequent episodes of hypoglycemia or renal failure because the lack of donors and islet survival. Moreover, patients transplanted with either whole pancreas or islets require of immune suppression to avoid the rejection of the transplant. Currently, advanced therapy medicinal products (ATMP), such as implantable devices, have been developed in order to reduce immune rejection response while increasing cell survival. To overcome these issues, ATMPs must promote vascularization, guaranteeing the nutritional contribution, while providing O₂ until vasculature can surround the device. Moreover, it should help in the immune-protection to avoid acute and chronic rejection. The transplanted cells or islets should be embedded within biomaterials with tunable properties like injectability, stiffness and porosity mimicking natural ECM structural characteristics. And finally, an infinitive cell source that solves the donor scarcity should be found such as insulin producing cells derived from mesenchymal stem cells (MSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Several companies have registered their ATMPs and future studies envision new prototypes. In this review, we will discuss the mechanisms and etiology of diabetes, comparing the clinical trials in the last decades in order to define the main characteristics for future ATMPs.

Multiple fractures and impaired bone metabolism in Wolfram syndrome: a case report

Wolfram Syndrome (WS) is a rare and lethal disease characterized by optic atrophy, diabetes mellitus, diabetes insipidus, and hearing loss. To date, osteoporotic related fractures have not been reported in affected patients. Here, we describe the case of a man affected by WS complicated by several bone fragility fractures. A 50-year-old Caucasian man was hospitalized because of tibia and fibula fractures. His clinical features included diabetes mellitus, diabetes insipidus, optic atrophy and deafness that were consistent with an unrecognized WS diagnosis, which was confirmed by the identification of a specific mutation in gene WFS1 encoding wolframin. Bone mineral density by phalangeal quantitative ultrasound demonstrated severe osteoporosis, with high serum levels of surrogate markers of bone turn-over. Previously unidentified rib fractures were also detected. To the best of our knowledge, this is the first report of osteoporotic related fractures in a patient affected by WS. Although no effective treatments are currently available to delay the progression of the disease, this case report suggests to evaluate fracture risk in the diagnostic work-up of WS.

Spotlight on ertugliflozin and its potential in the treatment of type 2 diabetes: evidence to date

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are the latest therapeutic strategy in the treatment of type 2 diabetes mellitus (T2DM). Using an insulin-independent mechanism (glycosuria), they reduce glucose toxicity and improve insulin sensitivity and β-cell function. The promising results obtained in clinical trials show that SGLT2 significantly improves glycemic control and provides greater cardiovascular protection, combined with a reduction in body weight and blood pressure (BP). This review focuses on ertugliflozin, a new, highly selective, and reversible SGLT2 inhibitor. Clinical trials published to date show that ertugliflozin, both as a monotherapy and as an add-on to oral antidiabetic agents, is safe and effective in reducing glycosylated hemoglobin (HbA1c), body weight, and BP in T2DM patients.

Antioxidant properties of drugs used in Type 2 diabetes management: could they contribute to, confound or conceal effects of antioxidant therapy?

Objectives: This is a narrative review, investigating the antioxidant properties of drugs used in the management of diabetes, and discusses whether these antioxidant effects contribute to, confound, or conceal the effects of antioxidant therapy.

Methods: A systematic search for articles reporting trials, or observational studies on the antioxidant effect of drugs used in the treatment of diabetes in humans or animals was performed using Web of Science, PubMed, and Ovid. Data were extracted, including data on a number of subjects, type of treatment (and duration) received, and primary and secondary outcomes. The primary outcomes were reporting on changes in biomarkers of antioxidants concentrations and secondary outcomes were reporting on changes in biomarkers of oxidative stress.

Results: Diabetes Mellitus is a disease characterized by increased oxidative stress. It is often accompanied by a spectrum of other metabolic disturbances, including elevated plasma lipids, elevated uric acid, hypertension, endothelial dysfunction, and central obesity. This review shows evidence that some of the drugs in diabetes management have both in vivo and in vitro antioxidant properties through mechanisms such as scavenging free radicals and upregulating antioxidant gene expression.

Conclusion: Pharmaceutical agents used in the treatment of type 2 diabetes has been shown to exert an antioxidant effect..

Effect of Betula pendula Leaf Extract on α-Glucosidase and Glutathione Level in Glucose-Induced Oxidative Stress

B. pendula leaf is a common ingredient in traditional herbal combinations for treatment of diabetes in southeastern Europe. Present study investigated B. pendula ethanolic and aqueous extract as inhibitors of carbohydrate hydrolyzing enzymes, as well as their ability to restore glutathione concentration in Hep G2 cells subjected to glucose-induced oxidative stress. Phytochemical analysis revealed presence of rutin and other quercetin derivatives, as well as chlorogenic acid. In general, ethanolic extract was richer in phenolic substances than the aqueous extract. Furthermore, a comprehensive analysis of antioxidant activity of two extracts (determined by DPPH and ABTS radical scavenging activity, total antioxidant activity, and chelating activity as well as ferric-reducing antioxidant power) has shown that ethanolic extract was better radical scavenger and metal ion reductant. In addition, ethanolic extract effectively increased cellular glutathione levels caused by hyperglycemia and inhibited α-glucosidase with the activity comparable to that of acarbose. Therefore, in vitro research using B. pendula plant extracts has confirmed their antidiabetic properties.

Spices in the management of diabetes mellitus

Diabetes mellitus (DM) remains a major health care problem worldwide both in developing and developed countries. Many factors, including age, obesity, sex, and diet, are involved in the etiology of DM. Nowadays, drug and dietetic therapies are the two major approaches used for prevention and control of DM. Compared to drug therapy, a resurgence of interest in using diet to manage and treat DM has emerged in recent years. Conventional dietary methods to treat DM include the use of culinary herbs and/or spices. Spices have long been known for their antioxidant, anti-inflammatory, and anti-diabetic properties. This review explores the anti-diabetic properties of commonly used spices, such as cinnamon, ginger, turmeric, and cumin, and the use of these spices for prevention and management of diabetes and associated complications.

Caenorhabditis elegans PAQR-2 and IGLR-2 Protect against Glucose Toxicity by Modulating Membrane Lipid Composition

In spite of the worldwide impact of diabetes on human health, the mechanisms behind glucose toxicity remain elusive. Here we show that C. elegans mutants lacking paqr-2, the worm homolog of the adiponectin receptors AdipoR1/2, or its newly identified functional partner iglr-2, are glucose intolerant and die in the presence of as little as 20 mM glucose. Using FRAP (Fluorescence Recovery After Photobleaching) on living worms, we found that cultivation in the presence of glucose causes a decrease in membrane fluidity in paqr-2 and iglr-2 mutants and that genetic suppressors of this sensitivity act to restore membrane fluidity by promoting fatty acid desaturation. The essential roles of paqr-2 and iglr-2 in the presence of glucose are completely independent from daf-2 and daf-16, the C. elegans homologs of the insulin receptor and its downstream target FoxO, respectively. Using bimolecular fluorescence complementation, we also show that PAQR-2 and IGLR-2 interact on plasma membranes and thus may act together as a fluidity sensor that controls membrane lipid composition.

Degeneration of Dopaminergic Neurons Due to Metabolic Alterations and Parkinson's Disease

The rates of metabolic diseases, such as type 2 diabetes mellitus (T2DM), obesity, and cardiovascular disease (CVD), markedly increase with age. In recent years, studies have reported an association between metabolic changes and various pathophysiological mechanisms in the central nervous system (CNS) in patients with metabolic diseases. Oxidative stress and hyperglycemia in metabolic diseases lead to adverse neurophysiological phenomena, including neuronal loss, synaptic dysfunction, and improper insulin signaling, resulting in Parkinson’s disease (PD). In addition, several lines of evidence suggest that alterations of CNS environments by metabolic changes influence the dopamine neuronal loss, eventually affecting the pathogenesis of PD. Thus, we reviewed recent findings relating to degeneration of dopaminergic neurons during metabolic diseases. We highlight the fact that using a metabolic approach to manipulate degeneration of dopaminergic neurons can serve as a therapeutic strategy to attenuate pathology of PD.

β-Cell Glucose Sensitivity Is Linked to Insulin/Glucagon Bihormonal Cells in Nondiabetic Humans

CONTEXT

Insulin resistance impacts virtually all tissues, including pancreatic β cells. Individuals with insulin resistance, but without diabetes, exhibit an increased islet size because of an elevated number of both β and α cells. Neogenesis from duct cells and transdifferentiation of α cells have been postulated to contribute to the β-cell compensatory response to insulin resistance.

OBJECTIVE

Our objective was to explore parameters that could potentially predict altered islet morphology.

METHODS

We investigated 16 nondiabetic subjects by a 2-hour hyperglycemic clamp to evaluate β-cell secretory function. We analyzed pancreas samples obtained during pancreatoduodenectomy in the same patients to examine glucagon and insulin double+ cells to assess islet morphology.

RESULTS

Among all the functional in vivo parameters of insulin secretion that were explored (basal, first phase and total secretion, glucose sensitivity, arginine-stimulated insulin secretion), β-cell glucose sensitivity was unique in exhibiting a significant correlation with both islet size and α-β double+ islet cells.

CONCLUSIONS

Our data suggest that poor β-cell glucose sensitivity is linked to islet transdifferentiation, possibly from α cells to β cells, in an attempt to cope with higher demands for insulin secretion. Understanding the mechanism(s) that underlies the adaptive response of the islet cells to insulin resistance is a potential approach to design tools to enhance functional β-cell mass for diabetes therapy.

High glucose-induced reactive oxygen species generation promotes stemness in human adipose-derived stem cells

BACKGROUND AIMS

Adipose-derived stem cells (ASCs) represent an important source of cell therapy to treat diabetic complications. However, hyperglycemia may alter several cellular functions, so the present study aimed to investigate the influence of a diabetic environment on the stemness and differentiation capabilities of ASCs.

METHODS

Human ASCs were obtained from subcutaneous adipose tissues of diabetic (dASCs) and nondiabetic donors (nASCs) and characterized. To reproduce an in vitro hyperglycemia environment, the nASCs were also cultured under prolonged high-glucose (HG; 4.5 g/L) or low-glucose (LG; 1.0 g/L) conditions.

RESULTS

The expression of cell surface markers in dASCs and nASC was similar and characteristic of mesenchymal stem cells. Although dASCs or HG-treated nASCs exhibited decreased proliferation, enhanced expression of the pluripotent markers Sox-2, Oct-4, and Nanog was observed. Moreover, HG-treated nASCs exhibited decreased cell migration, enhanced senescence, and significantly higher intracellular reactive oxygen species (ROS), whereas their adipogenic and osteogenic differentiation capacities remained comparable to LG-treated cells. With antioxidant treatment, HG-treated nASCs showed improved cell proliferative activity without stemness enhancement. This HG-induced biological response was associated with ROS-mediated AKT attenuation. When cultured in an appropriate induction medium, the HG-treated nASCs and dASCs exhibited enhanced potential of transdifferentiation into neuron-like cells.

DISCUSSION

Despite lower proliferative activity and higher senescence in a diabetic environment, ASCs also exhibit enhanced stemness and neurogenic transdifferentiation potential via a ROS-mediated mechanism. The information is important for future application of autologous ASCs in diabetic patients.

Hyperglycemic Stress and Carbon Stress in Diabetic Glucotoxicity

Diabetes and its complications are caused by chronic glucotoxicity driven by persistent hyperglycemia. In this article, we review the mechanisms of diabetic glucotoxicity by focusing mainly on hyperglycemic stress and carbon stress. Mechanisms of hyperglycemic stress include reductive stress or pseudohypoxic stress caused by redox imbalance between NADH and NAD(+) driven by activation of both the polyol pathway and poly ADP ribose polymerase; the hexosamine pathway; the advanced glycation end products pathway; the protein kinase C activation pathway; and the enediol formation pathway. Mechanisms of carbon stress include excess production of acetyl-CoA that can over-acetylate a proteome and excess production of fumarate that can over-succinate a proteome; both of which can increase glucotoxicity in diabetes. For hyperglycemia stress, we also discuss the possible role of mitochondrial complex I in diabetes as this complex, in charge of NAD(+) regeneration, can make more reactive oxygen species (ROS) in the presence of excess NADH. For carbon stress, we also discuss the role of sirtuins in diabetes as they are deacetylases that can reverse protein acetylation thereby attenuating diabetic glucotoxicity and improving glucose metabolism. It is our belief that targeting some of the stress pathways discussed in this article may provide new therapeutic strategies for treatment of diabetes and its complications.

Efficacy and safety of dapagliflozin, a sodium glucose cotransporter 2 (SGLT2) inhibitor, in diabetes mellitus

Although antidiabetic agents have been developed to target one or more of the core defects of type 2 diabetes mellitus (T2DM), many patients do not achieve glycemic goals. Inhibition of the sodium-glucose cotransporter 2 (SGLT2) induces glycosuria, reduces glucose toxicity and improves insulin sensitivity and β-cell function. As the mechanism of action of SGLT2 inhibitors is different from other agents and completely insulin-independent, the use of these drugs might potentially be efficacious alone or in combination with any other antidiabetic drug, including insulin. Dapagliflozin is a highly selective and reversible SGLT2 inhibitor approved for use in adult patients with T2DM as monotherapy in patients intolerant of metformin or as adjunctive therapy in patients inadequately controlled on existing antidiabetic medications, including insulin. A literature search conducted using PubMed identified key publications related to the use of dapagliflozin in the treatment of patients with diabetes mellitus. No date limits were applied. This review focuses on the safety and efficacy of this SGLT2 inhibitor. Dapagliflozin produces dose-related reductions in glycosylated hemoglobin (HbA1c) as monotherapy and as add-on to other antidiabetic agents, with significant reductions in body weight. Hypoglycemia is uncommon. Preliminary data from a phase 2 pharmacokinetic/pharmacodynamic study suggest that dapagliflozin may also improve glycemic control in patients with type 1 diabetes mellitus. Clinical trials published to date show that dapagliflozin is safe and effective as monotherapy or as an add-on to insulin or oral antidiabetic agents in patients with T2DM.

Necrotizing fasciitis in patients with diabetes mellitus: clinical characteristics and risk factors for mortality

Background

Necrotizing fasciitis (NF) is a rapidly progressive and life-threatening infection. This study aimed to investigate the clinical characteristics and mortality- associated factors in diabetic patients.

Methods

Detailed clinical information of 165 NF cases was retrospectively collected and analyzed in National Taiwan University Hospital between January 1997 and February 2013. We documented and compared the clinical features according to the presence of underlying diabetes mellitus, and we identified risk factors associated with mortality.

Results

There were 84 patients (51 %) with diabetes. The overall case fatality rate was 29.7 %, and we found no significant difference between the patients with or without diabetes. Compared with the nondiabetic patients, diabetic patients were older and exhibited higher serum levels of glucose and potassium on admission. Polymicrobial infection and monomicrobial NF caused by Klebsiella pneumoniae were also more frequently associated with diabetic patients. Moreover, diabetic NF patients exhibit a significantly higher chance of limb loss during hospitalization. In the combined diabetic and nondiabetic cohort, a high serum level of potassium (odds ratio, 2.2; 95 % confidence interval, 1.2 to 4.02; P = 0.011) on admission was independently associated with mortality, whereas positive blood culture on admission was associated with mortality in the diabetic cohort (odds ratio, 7.36; 95 % confidence interval, 1.66 to 32.54; P = 0.009).

Conclusions

Diabetic patients are more susceptible to NF caused by polymicrobial infection or K. pneumoniae, and they are more likely to receive limb amputation for infection control. Bacteraemia on admission is a significant risk factor for mortality in diabetic NF patients.

Bone metabolism and hand grip strength response to aerobic versus resistance exercise training in non-insulin dependent diabetic patients

BACKGROUND

Diabetes mellitus has been shown in many studies to be associated with reduced bone mass and an increased risk of fracture. Currently, our understanding of how to use exercise effectively in diabetic patients in prevention of osteoporosis is incomplete and has prompted our interest to identify the type of effective osteogenic exercise.

OBJECTIVE

The aim of this study was to compare the changes in handgrip strength and bone metabolism after 6 months between aerobic and resistance exercise training in non-insulin dependent diabetic patients in Jeddah area.

MATERIALS AND METHODS

One hundred non-insulin dependent diabetic male patients participated in this study and were divided into two equal groups; the first group (A) received aerobic exercise training, where the second group (B) received resistance exercise training. The program consisted of three sessions per week for six months.

RESULTS

The mean values of serum calcium and Hand grip strength were significantly increased, while the mean values of parathyroid hormone were significantly decreased in both groups .Also, there were significant differences between mean levels of the investigated parameters in group (A) and group (B) after treatment.

CONCLUSION

Aerobic exercise training on treadmill is appropriate to improve markers of bone metabolism and hand grip strength in non-insulin dependent diabetic patients.

Fructose Metabolism and Relation to Atherosclerosis, Type 2 Diabetes, and Obesity

A high intake of sugars has been linked to diet-induced health problems. The fructose content in sugars consumed may also affect health, although the extent to which fructose has a particularly significant negative impact on health remains controversial. The aim of this narrative review is to describe the body's fructose management and to discuss the role of fructose as a risk factor for atherosclerosis, type 2 diabetes, and obesity. Despite some positive effects of fructose, such as high relative sweetness, high thermogenic effect, and low glycaemic index, a high intake of fructose, particularly when combined with glucose, can, to a larger extent than a similar glucose intake, lead to metabolic changes in the liver. Increased de novo lipogenesis (DNL), and thus altered blood lipid profile, seems to be the most prominent change. More studies with realistic consumption levels of fructose are needed, but current literature does not indicate that a normal consumption of fructose (approximately 50–60 g/day) increases the risk of atherosclerosis, type 2 diabetes, or obesity more than consumption of other sugars. However, a high intake of fructose, particularly if combined with a high energy intake in the form of glucose/starch, may have negative health effects via DNL.

Circulating cell-free mitochondrial DNA as the probable inducer of early endothelial dysfunction in the prediabetic patient

Recent evidence has shown that 346million people in the world have diabetes mellitus (DM); this number will increase to 439million by 2030. In addition, current data indicate an increase in DM cases in the population between 40 and 59years of age. Diabetes is associated with the development of micro- and macro-vascular complications, derived from chronic hyperglycemia on the endothelium. Some reports demonstrate that people in a prediabetic state have a major risk of developing early endothelial dysfunction (ED). Today, it is accepted that individuals considered as prediabetic patients are in a pro-inflammatory state associated with endothelial and mitochondrial dysfunction. It is important to mention that impaired mitochondrial functionality has been linked to endothelial apoptosis and release of mitochondrial DNA (mtDNA) in patients with sepsis, cardiac disease, or atherosclerosis. This free mtDNA could promote ED, as well as other side effects on the vascular system through the activation of the toll-like receptor 9 (TLR9). TLR9 is expressed in different cell types (e.g., T or B lymphocytes, mastocytes, and epithelial and endothelial cells). It is localized intracellularly and recognizes non-methylated dinucleotides of viral, bacterial, and mitochondrial DNA. Recently, it has been reported that TLR9 is associated with the pathogenesis of lupus erythematosus, rheumatoid arthritis, and autoimmune diabetes. In this work, it is hypothesized that the increase in the levels of circulating mtDNA is the trigger of early ED in the prediabetic patient, and later on in the older patient with diabetes, through activation of the TLR9 present in the endothelium.

Pros and cons of fatty acids in bone biology

Despite the growing interest in deciphering the causes and consequences of obesity-related disorders, the mechanisms linking fat intake to bone behaviour remain unclear. Since bone fractures are widely associated with increased morbidity and mortality, most notably in elderly and obese people, bone health has become a major social and economic issue. Consistently, public health system guidelines have encouraged low-fat diets in order to reduce associated complications. However, from a bone point of view, mechanisms linking fat intake to bone alteration remain quite controversial. Thus, after more than a decade of dedicated studies, this timely review offers a comprehensive overview of the relationships between bone and fatty acids. Using clinical evidences as a starting-point to more complex molecular elucidation, this work highlights the complexity of the system and reveals that bone alteration that cannot be solved simply by taking ω-3 pills. Fatty acid effects on bone metabolism can be both direct and indirect and require integrated investigations. Furthermore, even at the level of a single cell, one fatty acid is able to trigger several different independent pathways (receptors, metabolites…) which may all have a say in the final cellular metabolic response.

Mangiferin inhibits endoplasmic reticulum stress-associated thioredoxin-interacting protein/NLRP3 inflammasome activation with regulation of AMPK in endothelial cells

BACKGROUND

Endothelial dysfunction is tightly associated with cardiovascular complications in diabetic patients. This study aims to investigate the effects of mangiferin on the regulation of endothelial homeostasis under endoplasmic reticulum stress (ER stress) conditions.

RESULTS

High glucose (25 mmol/L) exposure induced ER stress and promoted ROS production in endothelial cells. Mangiferin effectively inhibited ER stress-associated oxidative stress by attenuating IRE1α phosphorylation and reducing ROS production. In response to ER stress, thioredoxin-interacting protein (TXNIP) expression increased, followed by NLRP3 inflammasome activation and increased IL-1β secretion. Mangiferin treatment attenuated the expressions of TXNIP and NLRP3 and reduced IL-1β and IL-6 production, demonstrating its inhibitory effects on TXNIP/NLRP3 inflammasome activation. NLRP3 inflammasome activation is responsible for mitochondrial cell death. Mangiferin restored the loss of the mitochondrial membrane potential (Δψm) and inhibited caspase-3 activity, and thereby protected cells from high glucose-induced apoptosis. Moreover, mangiferin inhibited ET-1 secretion and restored the loss of NO production when cells were exposed to high glucose. Mangiferin enhanced AMPK phosphorylation and AMPK inhibitor compound C diminished its beneficial effects, indicating the potential role of AMPK in its action.

CONCLUSION

Our work showed the beneficial effects of mangiferin on the improvement of endothelial homeostasis and elucidated the molecular pathway through which mangiferin ameliorated endothelial dysfunction by inhibition of ER stress-associated TXNIP/NLRP3 inflammasome activation in endothelial cells.

SIGNIFICANCE

These findings demonstrated the beneficial effects of mangiferin on the regulation of endothelial homeostasis and indicated its potential application in the management of diabetic cardiovascular complications.

Adenosine receptor transcriptomic profile in cardiac tissue of a Zucker rat model

To evaluate the possible variations of adenosine receptor (AR) profile together with TNF-α and IL-6 mRNA in cardiac tissue of obese Zucker rats (OZR) during fasting conditions (fc) and during the induction of acute hyperglycemia (AH). OZR (O, n=21) and age-matched lean control rats (CO, n=18) were studied during fc (COfc, n=8; Ofc, n=13) and during the induction of AH (COAH, n=10; OAH, n=8). The histopathologic analysis performed on O and CO heart samples did not show abnormalities of myocardial structure. The AR transcriptomic profile was analyzed in O and CO by real-time polymerase chain reaction (PCR) and a significantly lower mRNA expression was observed for A2AR in O with respect to CO (p=0.047), while a significant upregulation was observed for A3R in O with respect to CO (p=0.002). No significant differences between O and CO were observed for TNF-α or IL-6. Correlations were found between glycemia and A1R (p=0.03) and A2BR (p=0.002); total cholesterol and A2BR (p=0.02) and A3R (p=0.0002), as well as between IL-6 and A1R (p=0.05) and TNF-α and A2AR (p<0.0001). The modulation of ARs in these settings could represent a promising approach to pharmacological treatment, which must be supported by diet restrictions and physical exercise.

Biofluid proteases profiling in diabetes mellitus

The investigation of protease relevance in biologic systems beyond catabolism of proteins and peptides to amino acids has stimulated interest as to their role in the pathogenesis of several disorders including diabetes mellitus (DM). Evaluation of proteases and the assessment of their activity in biofluids are fundamental to elucidate these proteolytic systems in DM and its related complications. In contrast to traditional immunoassay or substrate based approaches that targeted specific proteases and their inhibitors, the field of degradomics has provided a comprehensive approach to study these enzymes. Although the degradome contains over 500 proteases, very few have been associated with DM and its micro- and macrovascular complications. In this paper, we review these proteases and their respective inhibitors with emphasis on DM. It is likely that future research will expand these initial studies and look to develop high throughput automated technologies to identify and characterize biofluid proteases of diagnostic and prognostic value in other pathologies.

The mitochondrial O-linked N-acetylglucosamine transferase (mOGT) in the diabetic patient could be the initial trigger to develop Alzheimer disease

Diabetes mellitus (DM) is considered a risk factor for the development of Alzheimer disease (AD); however, how DM favors evolution of AD is still insufficiently understood. Hyperglycemia in DM is associated to an increase in mitochondrial reactive oxygen species (ROS) generation, as well as damage of hippocampal cells, reflected by changes in morphological and mitochondrial functionality. Similar mitochondrial damage has been observed when amyloid beta (Aβ) accumulates in the brain of AD patients. In DM, the excess of glucose in the brain induces higher activity of the hexosamine biosynthesis pathway (HBP), it synthesizes UDP-N-acetylglucosamine (UDP-GlcNAc), which is used by O-linked N-acetylglucosamine transferase (OGT) to catalyze O-GlcNAcylation of numerous proteins. Although O-GlcNAcylation plays an important role in maintaining structure and cellular functionality, chronic activity of this pathway has been associated with insulin resistance and hyperglycemia-induced glucose toxicity. Three different forms of OGT are known: nucleocytoplasmic (ncOGT), short (sOGT), and mitochondrial (mOGT). Previous reports showed that overexpression of ncOGT is not toxic to the cell; in contrast, overexpression of mOGT is associated with cellular apoptosis. In this work, we suggest that hyperglycemia in the diabetic patient could induce greater expression and activity of mOGT, modifying the structure and functionality of mitochondria in hippocampal cells, accelerating neuronal damage, and favoring the start of AD. In consequence, mOGT activity could be a key point for AD development in patients with DM.

The detrimental effects of acute hyperglycemia on myocardial glucose uptake

AIMS

Although acute hyperglycemic (AHG) episodes are linked to lower glucose uptake, underlying mechanisms remain unclear. We hypothesized that AHG triggers reactive oxygen species (ROS) production and increases non-oxidative glucose pathway (NOGP) activation, i.e. stimulation of advanced glycation end products (AGE), polyol pathway (PP), hexosamine biosynthetic pathway (HBP), PKC; thereby decreasing cardiac glucose uptake.

MAIN METHODS

H9c2 cardiomyoblasts were exposed to 25 mM glucose for 24h vs. 5.5mM controls ± modulating agents during the last hour of glucose exposure: a) antioxidant #1 for mitochondrial ROS (250 μM 4-OHCA), b) antioxidant #2 for NADPH oxidase-generated ROS (100 μM DPI), c) NOGP inhibitors - 100 μM aminoguanidine (AGE), 5 μM chelerythrine (PKC); 40 μM DON (HBP); and 10 μM zopolrestat (PP). ROS levels (mitochondrial, intracellular) and glucose uptake were evaluated by flow cytometry.

KEY FINDINGS

AHG elevated ROS, activated NOGPs and blunted glucose uptake. Transketolase activity (pentose phosphate pathway [PPP] marker) did not change. Respective 4-OHCA and DPI treatment blunted ROS production, diminished NOGP activation and normalized glucose uptake. NOGP inhibitory studies identified PKCβII as a key downstream player in lowering insulin-mediated glucose uptake. When we employed an agent (benfotiamine) known to shunt flux away from NOGPs (into PPP), it decreased ROS generation and NOGP activation, and restored glucose uptake under AHG conditions.

SIGNIFICANCE

This study demonstrates that AHG elicits maladaptive events that function in tandem to reduce glucose uptake, and that antioxidant treatment and/or attenuation of NOGP activation (PKC, polyol pathway) may limit the onset of insulin resistance.

Insulin resistance alters islet morphology in nondiabetic humans

Type 2 diabetes is characterized by poor glucose uptake in metabolic tissues and manifests when insulin secretion fails to cope with worsening insulin resistance. In addition to its effects on skeletal muscle, liver, and adipose tissue metabolism, it is evident that insulin resistance also affects pancreatic β-cells. To directly examine the alterations that occur in islet morphology as part of an adaptive mechanism to insulin resistance, we evaluated pancreas samples obtained during pancreatoduodenectomy from nondiabetic subjects who were insulin-resistant or insulin-sensitive. We also compared insulin sensitivity, insulin secretion, and incretin levels between the two groups. We report an increased islet size and an elevated number of β- and α-cells that resulted in an altered β-cell-to-α-cell area in the insulin- resistant group. Our data in this series of studies suggest that neogenesis from duct cells and transdifferentiation of α-cells are potential contributors to the β-cell compensatory response to insulin resistance in the absence of overt diabetes.

Interactions between mesenchymal stem cells, adipocytes, and osteoblasts in a 3D tri-culture model of hyperglycemic conditions in the bone marrow microenvironment

Recent studies have found that uncontrolled diabetes and consequential hyperglycemic conditions can lead to an increased incidence of osteoporosis. Osteoblasts, adipocytes, and mesenchymal stem cells (MSCs) are all components of the bone marrow microenvironment and thus may have an effect on diabetes-related osteoporosis. However, few studies have investigated the influence of these three cell types on each other, especially in the context of hyperglycemia. Thus, we developed a hydrogel-based 3D culture platform engineered to allow live-cell retrieval in order to investigate the interactions between MSCs, osteoblasts, and adipocytes in mono-, co-, and tri-culture configurations under hyperglycemic conditions for 7 days of culture. Gene expression, histochemical analysis of differentiation markers, and cell viability were measured for all cell types, and MSC-laden hydrogels were degraded to retrieve cells to assess their colony-forming capacity. Multivariate models of gene expression data indicated that primary discrimination was dependent on the neighboring cell type, validating the need for co-culture configurations to study conditions modeling this disease state. MSC viability and clonogenicity were reduced when mono- and co-cultured with osteoblasts at high glucose levels. In contrast, MSCs showed no reduction of viability or clonogenicity when cultured with adipocytes under high glucose conditions, and the adipogenic gene expression indicates that cross-talk between MSCs and adipocytes may occur. Thus, our unique culture platform combined with post-culture multivariate analysis provided a novel insight into cellular interactions within the MSC microenvironment and highlights the necessity of multi-cellular culture systems for further investigation of complex pathologies such as diabetes and osteoporosis.

Effect of a short-term exercise program on glycemic control measured by fructosamine test in type 2 diabetes patients

BACKGROUND

Glycated hemoglobin (A1C) and Fasting Plasma Glucose (FPG) are the two monitoring blood glucose tests most frequently used. However, both methods are shown to be insensitive to detect glycemic variations in short duration periods. Therefore, we aimed to assess the effect of a short-term exercise program on glycemic levels measured by fructosamine concentrations in type 2 diabetes patients.

METHODS

Eight volunteers (51.1 ± 8.2 years) underwent a supervised exercise program during eight weeks (3 d.wk-1, 50-60% of VO2 peak for 30-60 minutes). The body composition, VO2 peak, A1C, FPG, fructosamine and capillary blood glucose (CBG) were evaluated. We used ANOVA - One Way for repeated measures followed by Tukey post-hoc test and paired t test. P values <0.05 were considered significant.

RESULTS

We found statistical differences on the concentrations of fructosamine, VO2 peak and CBG. However, A1C and FPG showed no statistical difference. Fructosamine declined by 15% (57 μmol/L) between the beginning and the end of the study. Individually, 50% of the sample reached the reference values for the normality in fructosamine test. VO2 peak increased by 14.8% (3.8 ml.kg-1.min-1) and CBG decreased on an average of 34.4% (69.3 mg/dL).

CONCLUSIONS

Fructosamine test is effective in the evaluation of glucose with type 2 diabetes patients when undergoing a short exercise program, alternatively to the traditional A1C and FPG assessment. Our results are relevant in clinical practice, because the significant improvement in glycemic status can help to evaluate the inclusion of exercise as adjunct therapy to replace the prescription of additional drugs in poorly controlled patients.

Resveratrol protects DAergic PC12 cells from high glucose-induced oxidative stress and apoptosis: effect on p53 and GRP75 localization

Resveratrol (RESV), a polyphenolic natural compound, has long been acknowledged to have cardioprotective and antiinflammatory actions. Evidence suggests that RESV has antioxidant properties that reduce the formation of reactive oxygen species leading to oxidative stress and apoptotic death of dopaminergic (DAergic) neurons in Parkinson’s disease (PD). Recent literature has recognized hyperglycemia as a cause of oxidative stress reported to be harmful for the nervous system. In this context, our study aimed (a) to evaluate the effect of RESV against high glucose (HG)-induced oxidative stress in DAergic neurons, (b) to study the antiapoptotic properties of RESV in HG condition, and c) to analyze RESV’s ability to modulate p53 and GRP75, a p53 inactivator found to be under expressed in postmortem PD brains. Our results suggest that RESV protects DAergic neurons against HG-induced oxidative stress by diminishing cellular levels of superoxide anion. Moreover, RESV significantly reduces HG-induced apoptosis in DAergic cells by modulating DNA fragmentation and the expression of several genes implicated in the apoptotic cascade, such as Bax, Bcl-2, cleaved caspase-3, and cleaved PARP-1. RESV also prevents the pro-apoptotic increase of p53 in the nucleus induced by HG. Such data strengthens the correlation between hyperglycemia and neurodegeneration, while providing new insight on the high occurrence of PD in patients with diabetes. This study enlightens potent neuroprotective roles for RESV that should be considered as a nutritional recommendation for preventive and/or complementary therapies in controlling neurodegenerative complications in diabetes.

1-deoxynojirimycin inhibits glucose absorption and accelerates glucose metabolism in streptozotocin-induced diabetic mice

We investigated the role of 1-deoxynojirimycin (DNJ) on glucose absorption and metabolism in normal and diabetic mice. Oral and intravenous glucose tolerance tests and labeled ¹³C₆-glucose uptake assays suggested that DNJ inhibited intestinal glucose absorption in intestine. We also showed that DNJ down-regulated intestinal SGLT1, Na⁺/K⁺-ATP and GLUT2 mRNA and protein expression. Pretreatment with DNJ (50 mg/kg) increased the activity, mRNA and protein levels of hepatic glycolysis enzymes (GK, PFK, PK, PDE1) and decreased the expression of gluconeogenesis enzymes (PEPCK, G-6-Pase). Assays of protein expression in hepatic cells and in vitro tests with purified enzymes indicated that the increased activity of glucose glycolysis enzymes was resulted from the relative increase in protein expression, rather than from direct enzyme activation. These results suggest that DNJ inhibits intestinal glucose absorption and accelerates hepatic glucose metabolism by directly regulating the expression of proteins involved in glucose transport systems, glycolysis and gluconeogenesis enzymes.

Cooperative anti-diabetic effects of deoxynojirimycin-polysaccharide by inhibiting glucose absorption and modulating glucose metabolism in streptozotocin-induced diabetic mice

We had previously shown that deoxynojirimycin-polysaccharide mixture (DPM) not only decreased blood glucose but also reversed the damage to pancreatic β-cells in diabetic mice, and that the anti-hyperglycemic efficacy of this combination was better than that of 1-deoxynojirimycin (DNJ) or polysachharide alone. However, the mechanisms behind these effects were not fully understood. The present study aimed to evaluate the therapeutic effects of DPM on streptozotocin (STZ)-induced diabetic symptoms and their potential mechanisms. Diabetic mice were treated with DPM (150 mg/kg body weight) for 90 days and continued to be fed without DPM for an additional 30 days. Strikingly, decrease of blood glucose levels was observed in all DPM treated diabetic mice, which persisted 30 days after cessation of DPM administration. Significant decrease of glycosylated hemoglobin and hepatic pyruvate concentrations, along with marked increase of serum insulin and hepatic glycogen levels were detected in DPM treated diabetic mice. Results of a labeled (13)C6-glucose uptake assay indicated that DPM can restrain glucose absorption. Additionally, DPM down-regulated the mRNA and protein expression of jejunal Na(+)/glucose cotransporter, Na(+)/K(+)-ATPase and glucose transporter 2, and enhanced the activities as well as mRNA and protein levels of hepatic glycolysis enzymes (glucokinase, phosphofructokinase, private kinase and pyruvate decarboxylas E1). Activity and expression of hepatic gluconeogenesis enzymes (phosphoenolpyruvate carboxykinase and glucose-6-phosphatase) were also found to be attenuated in diabetic mice treated with DPM. Purified enzyme activity assays verified that the increased activities of glucose glycolysis enzymes resulted not from their direct activation, but from the relative increase in protein expression. Importantly, our histopathological observations support the results of our biochemical analyses and validate the protective effects of DPM on STZ-induced damage to the pancreas. Thus, DPM has significant potential as a therapeutic agent against diabetes.

Phalangeal quantitative ultrasound and metabolic control in pre-menopausal women with type 1 diabetes mellitus

BACKGROUND

Several studies have reported increased fracture risk in Type 1 diabetes mellitus (T1DM). Quantitative Ultrasound (QUS) provides information on the structure and elastic properties of bone, which are important determinants of fracture risk, along with bone mineral density.

AIM

To study phalangeal sites by QUS, examine bone turnover markers and analyze association between these factors with metabolic control in a population of pre-menopausal women with T1DM.

MATERIAL AND METHODS

Thirty-five T1DM pre-menopausal women (mean age 34.5 ± 6.8 yr) attending the Diabetic Outpatients Clinic in the Department of Internal Medicine, University of Messina, were consecutively enrolled and divided into two groups, taking into account the mean value of glycated hemoglobin in the last three years. Twenty healthy age-matched women served as controls. Phalangeal ultrasound measurements [Amplitude Dependent Speed of Sound (AD-SoS), Ultrasound Bone Profile Index (UBPI), TScore, Z-Score] were performed using a DBM Sonic Bone Profiler. Osteocalcin and deoxypyridinoline served as markers of bone formation and bone resorption, respectively.

RESULTS

T1DM women with poor metabolic control showed lower phalangeal QUS values compared to healthy controls (p<0.01) and T1DM women with good metabolic control (p<0.05). No significant differences in QUS measurements were detected between T1DM women with good metabolic control and healthy controls. Lower bone formation and increased bone resorption, although not statistically significant, were observed in patients with poor metabolic control in comparison to patients with good metabolic control.

CONCLUSIONS

Poor metabolic control may worsen the quality of bone in T1DM. Phalangeal QUS could be considered as a tool to screen T1DM women for osteoporosis in pre-menopausal age.