Combined Hyperglycemia Research Articles

Synergism of mechanisms underlying early-stage changes in retina function in male hyperglycemic db/db mice in the absence and presence of chemically-induced dyslipidemia

The study was designed to quantify retina function in a spontaneous mutation mouse model of diabetes, in which sustained dyslipidemia was induced chemically. The goal of the study was to identify if dyslipidemia in the presence of hyperglycemia resulted in either a synergistic, or a merely additive, exacerbation of retinal and visual dysfunctions in diabetes. Two cohorts of mice, male C57BL/6 and C57BL/KsJ-db/db mice were divided into two groups each. One group of each strain received the triblock copolymer, poloxamer 407 (P-407), administered by intraperitoneal injection (“WT P-407” and “db/db P-407” groups) with saline as a control in the remaining two groups (“WT” and “db/db” groups). Blood glucose, total cholesterol (TC) and total triglyceride (TG) levels were quantified using enzyme-based colorimetric assays. Retina function was measured using electroretinography (ERG) and visual acuity was determined by behaviorally assessing parameters of the optomotor reflex. TC and TG levels were normal in both saline controls (WT) and db/db mice but were significantly elevated in the WT P-407 group (p < 0.01 for TC; p < 0.001 for TG), while levels of the same lipids were further elevated in the db/db P-407 group when compared to the WT P-407 group levels (p < 0.001 for both TC and TG). Behavioral assessment of the optomotor reflex indicated reduced visual acuity for the db/db P-407 group when compared to either the WT P-407 or the db/db groups (p < 0.001, p < 0.0001). ERG measurements of scotopic retina function showed a significant decline in the scotopic b-wave amplitude of the WT P-407 animals (p < 0.01) and a further reduction for the db/db P-407 group when compared to controls (p < 0.0001). Very significant, strong correlations between scotopic b-wave amplitude and implicit time to TC (r = − 0.8376, p = < 0.0001 and r = 0.7069, p = 0.0022, respectively) and TG levels (r = − 0.8554, p = < 0.0001 and r = 0.7150, p = 0.0019, respectively) were found. Dyslipidemia in the presence of hyperglycemia synergistically exacerbated the severity of retinal dysfunction in diabetes. P-407 administration significantly elevated plasma TC and TG levels in male wild-type (WT) and diabetic mice (db/db), but the resulting hyperlipidemia was more significantly pronounced in the diabetic mice. While elevated plasma lipid and blood glucose levels were individually correlated with a decline in retinal function, the combination of both exacerbated retinal dysfunction. This model of combined hyperglycemia and dyslipidemia can be used to dissect individual contributions of features of the metabolic syndrome to the pathogenesis of retinal dysfunction in diabetes.

Advanced maternal age (AMA) and 75 g oGTT glucose levels are pedictors for Insulin therapy in women with gestational diabetes (GDM).

Gestational diabetes (GDM) is a common complication during pregnancy that is strongly associated with adverse fetal and maternal outcomes. Advanced maternal age (≥35 years) is a known risk factor for GDM. Studies advocate that GDM comprises distinctive metabolic entities, suggesting an individualized approach based on early pregnancy characteristics (such as 75 g oGTT values, maternal age, obstetric history). The oGTT blood glucose levels of 1,664 women were categorized into isolated fasting hyperglycemia (GDM-IFH), isolated postprandial hyperglycemia (GDM-IPH) and combined hyperglycemia (GDM-CH), using the levels of the fasting, 1 h and 2 h values after glucose application. These three subtypes were analysed regarding baseline characteristics as well as fetal and maternal outcome in the context of maternal age. This analysis reveals that the 75 g oGTT levels and maternal age can distinguish metabolic phenotypes in women with GDM. The overall rate of Insulin therapy required was higher in women from the GDM-CH group and increased with maternal age (31.7 %, 38.2 %, <35 years,≥35-39 years respectively, vs. total Insulin rate 22.3 %, p-value <0.001). Women≥35 years displayed a significantly higher caesarean delivery (CD) rate (<35 years 34.6 %, 38.4 %, 41.1 % vs.≥35 years 54.8 %, 47.6 %, 46.5 %, GDM-IFH, GDM-IPH, GDM-CH respectively, p-value <0.001). Women with fasting hyperglycemia, especially those with combined hyperglycemia and AMA display a higher risk for unfavorable perinatal outcome. A categorization based on oGTT values and maternal age, as well as other characteristics can facilitate a basis for clinical risk stratification. Women at risk should receive an individualized and intensified perinatal care as well as interventional therapies.

Glucose Levels of the Oral Glucose Tolerance Test (oGTT) Can Predict Adverse Pregnancy Outcomes in Women with Gestational Diabetes (GDM).

Gestational diabetes (GDM) is a common pregnancy complication defined as a glucose intolerance diagnosis during pregnancy. GDM is strongly associated with adverse fetal and maternal outcomes. In Germany, to screen and diagnose GDM we use a 1 h 50 g oGCT (oral glucose challenge test) followed by a 2 h 75 g oGTT if the first was pathological. This analysis examines the correlation of 75 g oGTT glucose levels and fetomaternal outcome. Data from 1664 patients from a gestational diabetes consultation clinic at the Charité University Hospital in Berlin, Germany, were analyzed retrospectively from 2015 to 2022. The 75 g oGTT blood glucose levels were categorized into isolated fasting hyperglycemia (GDM-IFH), isolated post-load hyperglycemia (GDM-IPH) and combined hyperglycemia (GDM-CH), using the levels of the fasting, 1 h and 2 h values, after glucose application. These subtypes were compared based on their baseline characteristics as well as fetal and maternal outcome. GDM-IFH and GDM-CH women displayed higher pre-conceptional BMI and required insulin therapy more frequently (p < 0.001). The GDM-IFH group was at higher risk of having a primary cesarean section (p = 0.047), while GDM-IPH women were significantly more likely to have an emergent cesarean section (p = 0.013). The offspring of GDM-IFH and GDM-CH women were born with a significantly higher mean birthweight (p < 0.001) and birth weight percentiles (p < 0.001) and were at increased risk of being large for gestational age (LGA) (p = 0.004). Women from the GDM-IPH group delivered significantly more neonates who were small for gestational age (p = 0.027) or with low fetal weight <30th percentile (p = 0.003). This analysis shows a strong association between the glucose response pattern in the 75 g oGTT and adverse perinatal fetomaternal outcome. The differences among the subgroups, specifically concerning insulin therapy, mode of delivery and fetal growth, suggest an individualized approach to prenatal care after a GDM diagnosis.

Human IAPP is a contributor to painful diabetic peripheral neuropathy.

Peripheral neuropathy is a frequent complication of type 2 diabetes mellitus (T2DM). We investigated whether human islet amyloid polypeptide (hIAPP), which forms pathogenic aggregates that damage pancreatic islet β cells in T2DM, is involved in T2DM-associated peripheral neuropathy. In vitro, hIAPP incubation with sensory neurons reduced neurite outgrowth and increased levels of mitochondrial reactive oxygen species. hIAPP-transgenic mice, which have elevated plasma hIAPP levels without hyperglycemia, developed peripheral neuropathy as evidenced by pain-associated behavior and reduced intraepidermal nerve fiber (IENF) density. Similarly, hIAPP Ob/Ob mice, which have hyperglycemia in combination with elevated plasma hIAPP levels, had signs of neuropathy, although more aggravated. In wild-type mice, intraplantar and intravenous hIAPP injections induced long-lasting allodynia and decreased IENF density. Non-aggregating murine IAPP, mutated hIAPP (pramlintide), or hIAPP with pharmacologically inhibited aggregation did not induce these effects. T2DM patients had reduced IENF density and more hIAPP oligomers in the skin compared with non-T2DM controls. Thus, we provide evidence that hIAPP aggregation is neurotoxic and mediates peripheral neuropathy in mice. The increased abundance of hIAPP aggregates in the skin of T2DM patients supports the notion that hIAPP is a potential contributor to T2DM neuropathy in humans.

Characteristics of gestational diabetes subtypes classified by oral glucose tolerance test values.

BackgroundIn clinical practice, gestational diabetes mellitus (GDM) is treated as a homogenous disease but emerging evidence suggests that the diagnosis of GDM possibly comprises different metabolic entities. In this study, we aimed to assess early pregnancy characteristics of gestational diabetes mellitus entities classified according to the presence of fasting and/or post‐load hyperglycaemia in the diagnostic oral glucose tolerance test performed at mid‐gestation.MethodsIn this prospective cohort study, 1087 pregnant women received a broad risk evaluation and laboratory examination at early gestation and were later classified as normal glucose tolerant (NGT), as having isolated fasting hyperglycaemia (GDM‐IFH), isolated post‐load hyperglycaemia (GDM‐IPH) or combined hyperglycaemia (GDM‐CH) according to oral glucose tolerance test results. Participants were followed up until delivery to assess data on pharmacotherapy and pregnancy outcomes.ResultsWomen affected by elevated fasting and post‐load glucose concentrations (GDM‐CH) showed adverse metabolic profiles already at beginning of pregnancy including a higher degree of insulin resistance as compared to women with normal glucose tolerance and those with isolated defects (especially GDM‐IPH). The GDM‐IPH subgroup had lower body mass index at early gestation and required glucose‐lowering medications less often (28.9%) as compared to GDM‐IFH (47.8%, P = .019) and GDM‐CH (54.5%, P = .005). No differences were observed in pregnancy outcome data.ConclusionsWomen with fasting hyperglycaemia, especially those with combined hyperglycaemia, showed an unfavourable metabolic phenotype already at early gestation. Therefore, categorization based on abnormal oral glucose tolerance test values provides a practicable basis for clinical risk stratification.

Combination of hyperglycaemia and hyperlipidaemia induces endothelial dysfunction: Role of the endothelin and nitric oxide systems.

Endothelial dysfunction (ED) is a key feature of diabetes and is a major cause of diabetic vasculopathy. Diabetic patients who also exhibit hyperlipidaemia suffer from accelerated vascular complications. While the deleterious effects of high glucose levels (HG) and hyperlipidaemia alone on ED are well established, the effects of combined hyperlipidaemia and HG have not been thoroughly studied. Therefore, the current study examines whether HG and hyperlipidaemia exert synergistic ED, and explores the mechanisms underlying this phenomenon. We applied multi‐disciplinary approaches including cultured HUVECs and HMEC‐1 as well as knockout mice CByJ.129S7(B6)‐Ldlrtm1Her/J (LDLR−/−) to investigate the mechanisms underlying combined HG and hyperlipidaemia‐induced ED. Incremental doses of glucose in the presence or absence of OxLDL were added to HUVECs and HMEC‐1. After 5 days, the status of nitric oxide (NO) and endothelin (ET)‐1 systems as well as their signal transduction were assessed using Western blot, ELISA and immunoreactive staining. The effects of chronic combination of HG and hyperlipidaemia on endothelial integrity and function as well as alterations in circulatory NO and ET‐1 systems were examined in knockout mice LDLR−/− and their wild‐type. HUVEC cells exposed to HG and OxLDL displayed enhanced ET‐1 production, more than HG or OxLDL when added alone. Overproduction of ET‐1 stems from up‐regulation of endothelin converting enzyme (ECE)‐1 as observed under these conditions. In contrast, combination of HG and OxLDL dramatically decreased both total endothelial NO synthase (eNOS) by 60%, and activated eNOS (peNOS) by 80%. Moreover, NRF2 decreased by 42% and its active form (pNRF2) by 56%, as compared to baseline. Likewise, ETB levels decreased by 64% from baseline on endothelial cells. Furthermore, diabetic LDLR−/− mice displayed a higher blood pressure, plasma triglycerides, cholesterol, ET‐1 and NO2/NO3 levels, when compared with normoglycemic LDLR−/− and BALB mice. Combined hyperglycaemia and hyperlipidaemia activates the ET system and attenuates the nitric oxide system with the Nrf2 signalling pathway. These findings suggest that perturbations in these paracrine systems may contribute to ED.

Association Between Abnormal Glycemic Phenotypes and Microvascular Complications of Type 2 Diabetes Mellitus Outpatients in China.

PurposeThe objective of this study was to investigate the association of abnormal glycemic phenotypes with microvascular complications in type 2 diabetes patients.Participants and MethodsA total of 24,266 participants who were from the multicenter cross-sectional survey of China National HbA1c Surveillance System across China were included in the present study. Diabetes patients with abnormal glucose were divided into three groups according to phenotype: isolated fasting hyperglycemia (IFH), isolated postprandial hyperglycemia (IPH), or combined hyperglycemia (CH). The main outcomes were isolated diabetic retinopathy, isolated diabetic nephropathy, and combined diabetic retinopathy with nephropathy. Multivariate logistic regression was used to assess the association of abnormal glycemic phenotypes with microvascular complications.ResultsThe CH phenotype had the highest prevalence of isolated diabetic retinopathy, isolated diabetic nephropathy and combined diabetic retinopathy with nephropathy, followed by IPH. Multivariate analysis showed that the CH phenotype was associated with the highest risk of isolated diabetic retinopathy (OR: 1.20, 95% CI: 1.02–1.41), isolated diabetic nephropathy (OR: 1.59, 95% CI: 1.27–2.01) and combined diabetic retinopathy with nephropathy (OR: 1.93, 95% CI: 1.44–2.59). More importantly, participants with IPH phenotype also showed significantly higher risks of isolated diabetic retinopathy (OR: 1.16, 95% CI: 1.05–1.28), isolated diabetic nephropathy (OR: 1.37, 95% CI: 1.09–1.37) and combined diabetic retinopathy with nephropathy (OR:1.64, 95% CI: 1.21–2.21) compared to the IFH phenotype. After stratifying by age, sex, diabetes duration and BMI, the higher risks of isolated diabetic retinopathy, isolated diabetic nephropathy and combined diabetic retinopathy with nephropathy were confirmed in IPH phenotype group, compared to the IFH phenotype group.ConclusionDiabetic patients with IPH phenotype had higher risks of isolated diabetic retinopathy, isolated diabetic nephropathy and combined diabetic retinopathy with nephropathy compared with the participants phenotype of IFH, but lower than the phenotype of CH.

Cannabinoid-profiled agents improve cell survival via reduction of oxidative stress and inflammation, and Nrf2 activation in a toxic model combining hyperglycemia+Aβ1-42 peptide in rat hippocampal neurons

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder linked to various converging toxic mechanisms. Evidence suggests that hyperglycemia induces oxidative stress, mitochondrial dysfunction, inflammation and excitotoxicity, all of which play important roles in the onset and progression of AD pathogenesis. The endocannabinoid system (ECS) orchestrates major physiological responses, including neuronal plasticity, neuroprotection, and redox homeostasis, to name a few. The multi-targeted effectiveness of the ECS emerges as a potential approach to treat AD. Here we characterized the protective properties of the endocannabinoids arachidonylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), the synthetic cannabinoids CP 55–940 and WIN 55,212–2, and the fatty acid amide hydrolase (FAAH) inhibitor URB597, on a combined hyperglycemia + oligomeric amyloid β peptide (Aβ1-42) neurotoxic model in primary hippocampal neurons which exhibit several AD features. Cells were treated with cannabinoid agents at increased concentrations (1 nM–1 μM) for 6 h, and then co-treated with 150 mM glucose (GLU, 24 h), followed by incubation with 500 nM Aβ1-42 (24 h). Cell viability/survival, reactive oxygen species (ROS) levels, antioxidant enzyme (SOD, CAT, GPx and GRx) activities, biological products of oxidative damage (AGE and HNE adducts) and nitrosative stress (3-NT), several endpoints of inflammation (iNOS, IL-1β and TNF-α), amyloid quantification, mitochondrial membrane potential, and the involvement of the Nrf2 pathway, were all evaluated. The combined high glucose + amyloid beta 1–42 (GLU + Aβ1-42) condition decreased cell viability and mitochondrial membrane potential, while augmenting oxidative damage and inflammation. All agents tested preserved cell viability and stimulated mitochondrial membrane potential, while reducing all the evaluated toxic endpoints in a differential manner, with URB597 showing the highest efficacy. The neuroprotective efficacy of all cannabinoid agents, except for URB597, led to partial recruitment of specific antioxidant activity and Nrf2 pathway regulation. Our results support the neuroprotective potential of these agents at low concentrations against the damaging effects of GLU + Aβ1-42, affording new potential modalities for the design of AD therapies.

Evaluation of a follow-up program for diabetes after hospital discharge

Given the higher rate of hospital admissions among diabetic patients, discharge should be used to optimize outpatient treatment. We evaluate a follow-up program for diabetic patients after hospital discharge to determine the evolution of glycemic control. Retrospective collection of data on 375 diabetic patients enrolled in the follow-up program for optimization treatment: telephonic follow-up where treatment was adjusted if needed; and three months after discharge an in-person consultation was scheduled. Factors potentially associated with a 1% improvement in HbA1c were studied by multivariate logistic regression. Seventy-three percent of enrolled patients completed the follow-up program; each patient received an average of 4.6 phone calls. Globally, basal mean HbA1c was significantly lower three months later regarding the initial value (8.6 vs. 7.2%); the most relevant lowering was found in the group of hyper-glycemia by poor metabolic control (from 9.9 to 7.7%), combined hyperglycemia (from 9.3 to 7.3%) and debut (from 8.3 to 6.4%). Twenty percent of patients reported capillary hypoglycemia, with two severe events. A shorter duration of diabetes, absence of corticotherapy and absence of hypoglycemia during the follow-up period were independent predictors for a 1% reduction in three-months HbA1c. In patients whose treatment is changed on hospital discharge, a program allowing frequent treatment adjustment would improve HbA1c levels. These results could help to organize health resources more rationally.

Higher blood pressure predicts diabetes and enhances long-term risk of cardiovascular disease events in individuals with impaired glucose tolerance: Twenty-three-year follow-up of the Daqing diabetes prevention study.

BackgroundHypertension is more prevalent in subjects with impaired glucose tolerance (IGT), but whether higher blood pressure per se or the mild hyperglycemia in combination with the hypertension enhanced the risk of cardiovascular disease (CVD) remains unclear.MethodsFive hundred and sixty‐eight participants with IGT in the original Daqing diabetes prevention study, 297 with hypertension (HBP) and 271 without hypertension (NBP), were enrolled in 1986 and the intervention phase lasted for 6 years. In 2009, they were followed up to assess the outcomes of cardiovascular events (including stroke and myocardial infarction) and incidence of diabetes.ResultsOver 23 years, the incidence of diabetes was 93.9/1000 person‐years in HBP and 72.2/1000 person‐years in the NBP group, with an age‐ and sex‐adjusted hazard ratio of 1.26 (95% confidence interval [CI], 1.04‐1.54, P = 0.02). The yearly incidence of CVD events was 27.7/1000 person‐years and 16.6/1000 person‐years, indicating a 35% higher risk in HBP than in the NBP group (95% CI, 1.01‐1.81; P = 0.04). Cox proportional hazard analysis showed that a 10‐mm Hg increase of the baseline systolic blood pressure was associated with 9% increased risk of the development of diabetes (P = 0.02), together with a 7% higher risk of the CVD events (P = 0.02).ConclusionsHypertension predicted diabetes and enhances long‐term risk of CVD events in patients with IGT. An individualized strategy that targets hypertension as well as hyperglycemia is needed for diabetes and its cardiovascular complications.

Regulation of Lipid Regulator ANGPTL8 Gene Transcript by Insulin Is Mediated by C/EBPß, and ANGPTL8 Deficiency Improves Glucose Homeostasis in Mice

Angiopoietin-like protein 8 (ANGPTL8) is a novel circulating protein synthesized by the liver and adipose tissue and plays a key role in regulating the plasma lipid profiles. Its expression is regulated acutely by fasting and refeeding in humans and animals. However, the molecular and physiological mechanisms, which regulate its expression, remain largely unknown. In this study, we investigated the regulation of ANPTL8 by insulin and glucose in multiple cellular and animal systems. Interestingly, insulin alone rapidly and dose-dependently increased ANGPTL8 gene expression in both cultured hepatocytes and mature adipocytes, while high glucose combined with insulin presented further stimulation on ANGPTL8 only in adipocytes. In mice, 2-hour euglycemic-hyperinsulinemic and hyperglycemic-hyperinsulinemic clamps markedly stimulated ANGPTL8 mRNA levels in liver to a similar extent. However, only combined hyperglycemia-/hyperinsulinemia caused a significant elevation of ANGPTL8 gene transcript in mouse adipose tissue. These findings imply that distinct pathways are responsible for the effects of insulin and glucose on ANGPTL8 expression in liver and adipose tissue. By cloning the ANGPTL8 gene promoter fragment into a luciferase reporter vector, we discovered that insulin-induced ANGPTL8 gene transcript was mediated by the CCAAT/enhancer-binding protein beta (C/EBPβ) transcription factor, which is likely through Janus Kinase 2 (JAK2) pathway. We also observed that AMPK activation had an inhibitory effect on insulin-induced ANGPTL8 gene expression; this could explain, in part, the low ANGPTL8 levels during fasting. Finally, in mice ANGPTL8 knockout did not alter body weight or food intake compared to wild type littermates, but significantly improved glucose tolerance in diet induced obese mice. This beneficial effect on glucose tolerance most likely is explained by the reduction in serum FFA and triglyceride levels. Disclosure L. Zhang: None. M. Abdul-Ghani: None. R.A. DeFronzo: Speaker's Bureau; Self; AstraZeneca, Novo Nordisk Inc.. Advisory Panel; Self; AstraZeneca, Novo Nordisk Inc., Janssen Pharmaceuticals, Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Elcelyx Therapeutics, Inc., Intarcia Therapeutics, Inc.. Research Support; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Janssen Pharmaceuticals, Inc., Takeda Pharmaceuticals U.S.A., Inc.. L. Norton: None.

982: Blood glucose patterns and treatment response in women with gestational diabetes treated with glyburide

Given its mechanism of action, glyburide is thought to be more effective in treating postprandial hyperglycemia. We investigated whether pre-treamtent glucose patterns were associated with differences in glycemic control or fetal growth in women with GDM who are treated with glyburide. Pre-treatment self-monitored glucose patterns (isolated fasting, isolated postprandial, or combined elevations) were characterized among a retrospective cohort of 576 women with GDM who were treated with glyburide. Women were grouped based on having more than 33% of their pre-treatment fasting values exceeding 95 mg/dL and/or pre-treatment postprandial values exceeding 140 mg/dL. Maternal characteristics including self-monitored glucose, medication and pregnancy outcomes were collected. Bivariate, linear, and logistic regression analyses were used to assess the association between glycemic patterns and pregnancy outcomes. In women with GDM treated with glyburide, 213/576 (37%) had isolated fasting elevations, 76 (13.2%) had isolated postprandial elevations, and 287 (49.8%) had combined elevations. Women with isolated fasting and post-prandial hyperglycemia were less likely to require daily glyburide dose ≥10 mg compared to women with combined hyperglycemia (16 vs 14 vs 31%, p<0.0001), and glyburide failure was lowest in women with isolated fasting and increased with isolated post-prandial and combined elevations (2 vs 9 vs 16%, p<0.0001). The proportion of women with mean fasting glucose ≥95mg/dL and postprandial ≥140mg/dL decreased for all groups with advancing gestation and was highest in women with pre-treatment combined hyperglycemia (p<0.001) (Figure). Using isolated post-prandial as the referent, birth weight z-scores were similar in women with isolated fasting (β 0.18, 95% CI -0.09-0.46, p=0.19) but higher in combined hyperglycemia (β 0.34, 95% CI 0.07-0.61, p=0.01) after adjusting for maternal race, pre-pregnancy BMI, and gestational weight gain. There were no differences in neonatal morbidity by pre-treatment blood sugar patterns. These findings suggest that using glyburide to treat fasting hyperglycemia in future clinical trials may be reasonable. Combined hyperglycemia is associated with higher rates of suboptimal control, treatment failure, and higher birth weight z-scores.

Effect of combined dyslipidemia and hyperglycemia on diabetic peripheral neuropathy in alloxan-induced diabetic WBN/Kob rats.

Clinical and experimental research have suggested that dyslipidemia aggravates diabetic peripheral neuropathy (DPN). However, whether dyslipidemia is a risk factor for DPN remains unclear. To investigate the effect of dyslipidemia on DPN, morphological features of peripheral nerves were analyzed in diabetic rats treated with a high-fat diet (HFD). Male rats were divided into four groups: nondiabetic rats (N), alloxan-induced diabetic rats (AL), diabetic rats treated with an HFD (AH), and nondiabetic rats treated with an HFD (HF). Combined hyperglycemia and dyslipidemia (AH group) induced a significant increase in plasma triglyceride and cholesterol levels. In addition, the combined effects contributed to a reduction in myelin size and a reduction in myelin thickness as indicated on sensory sural nerve histograms. There was also a reduction in the size of motor nerve axons when compared with the effects of hyperglycemia or dyslipidemia alone. However, the sensory nerve conduction velocity in the AH group was slightly but not significantly lower than those in the HF and AL groups. These results suggest that combined hyperglycemia and dyslipidemia induced mild peripheral motor and sensory nerve lesions, without significantly affecting sensory nerve conduction velocity.

Hyperglycemia and high nitric oxide level induced oxidative stress in the brain and molecular alteration in the neurons and glial cells of laboratory mouse, Mus musculus

Chronic hyperglycemia (glucotoxicity) is reported to have detrimental effects on various brain functions leading to neurodegenerative changes. However, the effect of hyperglycemia in combination with high nitric oxide (NO) level (reported to be increased during glucotoxicity), on brain functions is not clear yet. The present study was designed to investigate the effects of hyperglycemic drug Streptozotocin (STZ) and NO donor Sodium nitroprusside (SNP) on the brain of laboratory mouse, Mus musculus. Effects of these conditions were studied on the markers of oxidative stress, NF-κB signalling and the markers of neuronal and glial cell activation/inflammation. Results indicate increased level of MDA and altered antioxidant enzymes activity in both the treated groups compared to control but high levels of AGEs, AOPP and AR activity (markers of diabetic complications) were observed in STZ group only. On the other hand, while STZ group showed decreased IL-6 level, it was increased in SNP group but IFN-ϒ level increased in both the treated groups compared to control. Further, in addition to alterations in the expressions of iNOS, IKKβ, IKBα and NF-κB subunits (RelA-p65/RelB-p50) observed in the neurons and glial cells of different brain regions (hypothalamus, basolateral amygdala and cerebral cortex), enhanced expression of microglial CD11b and astrocytic GFAP was also found in both the treated groups compared to control.Present findings led us to conclude that both hyperglycemia and high NO level causes oxidative stress in addition to molecular alteration in the neurons and glial cells. It is suggested that high blood glucose and NO level induced oxidative stress may lead to neuroinflammation possibly via NF-κB signalling.

Targeting HSP90 Ameliorates Nephropathy and Atherosclerosis Through Suppression of NF-κB and STAT Signaling Pathways in Diabetic Mice.

Heat shock proteins (HSPs) are induced by cellular stress and function as molecular chaperones that regulate protein folding. Diabetes impairs the function/expression of many HSPs, including HSP70 and HSP90, key regulators of pathological mechanisms involved in diabetes complications. Therefore, we investigated whether pharmacological HSP90 inhibition ameliorates diabetes-associated renal damage and atheroprogression in a mouse model of combined hyperglycemia and hyperlipidemia (streptozotocin-induced diabetic apolipoprotein E-deficient mouse). Treatment of diabetic mice with 17-dimethylaminoethylamino-17-demethoxygeldanamycin (DMAG, 2 and 4 mg/kg, 10 weeks) improved renal function, as evidenced by dose-dependent decreases in albuminuria, renal lesions (mesangial expansion, leukocyte infiltration, and fibrosis), and expression of proinflammatory and profibrotic genes. Furthermore, DMAG significantly reduced atherosclerotic lesions and induced a more stable plaque phenotype, characterized by lower content of lipids, leukocytes, and inflammatory markers, and increased collagen and smooth muscle cell content. Mechanistically, the renoprotective and antiatherosclerotic effects of DMAG are mediated by the induction of protective HSP70 along with inactivation of nuclear factor-κB (NF-κB) and signal transducers and activators of transcription (STAT) and target gene expression, both in diabetic mice and in cultured cells under hyperglycemic and proinflammatory conditions. In conclusion, HSP90 inhibition by DMAG restrains the progression of renal and vascular damage in experimental diabetes, with potential implications for the prevention of diabetes complications.

The hyperglycemic and hyperinsulinemic combo gives you diabetic kidney disease immediately. Focus on “Combined acute hyperglycemic and hyperinsulinemic clamp induced profibrotic and proinflammatory responses in the kidney”

diabetic kidney disease (DKD) is the leading cause of end-stage kidney failure in the United States (11). Clinically, nephropathy induced by diabetes is characterized by albumin in the urine and declining glomerular filtration rate. On histological examination, diabetic kidney disease is a glomerular disease defined by mesangial expansion, nodular sclerosis, arterial hyalinosis (arteriolar thickening by deposition of pink hyaline material) leading to glomerulosclerosis and tubulointerstitial fibrosis. DKD is caused by hyperglycemia (HG) as reducing the glycohemoglobin levels from 9 to 7% in patients with type 1 diabetes resulted in a greater than 50% decrease in nephropathy development (3). However, recent studies of patients with type 2 diabetes failed to show a significant reduction in DKD progression when the glycohemoglobin target was reduced below 7% (4). Many of us would like to understand the reason for this surprising difference in nephropathy development and progression. One interpretation is that hyperglycemia is just one of the factors that play a role in the development of diabetic complications in type 2 diabetes and that hyperinsulinemia (HI), insulin resistance, and adiponectin could be equally important. In the current edition of the journal, Mariappan et al. (8) examine the effect of acute (7 h) combined hyperglycemia and hyperinsulinemia on profibrotic and proinflammatory gene expression in rat kidneys (8). The authors describe an approximately twofold increase in urinary isoprostane levels indicative of increased renal oxidative stress under these conditions. They observed a significant increase in renal TGF-β expression and its downstream mediator phospho-Smad3 (8). The expression of fibronectin and β1-laminin was also increased even after this short period of HI/HG. Increased expression of phosphorylated mTOR, S6 kinase, ERK, eIF4E, eIF4A are likely responsible for the increased matrix protein synthesis and kidney enlargement. The authors went on to identify the TLR4/Myd88 and NF-κB pathways as responsible for the increased cytokine expression in the context of hyperglycemia and hyperinsulinemia. In summary, the authors provide compelling evidence that acute HI combined with HG regulate the expression of multiple pathways known to play roles in DKD development. Unfortunately, the authors neglected to provide results from control rats exposed to hyperglycemia or hyperinsulinemia alone; thus, we cannot fully conclude whether these effects are mediated by glucose or the increased insulin levels. For example, we are left to wonder whether reactive oxygen species release is higher in HG/HI animals or lower compared with HG rats. In addition, the length of the “acute” treatment warrants further scrutiny of the time course of these changes. Do changes occur only acutely or are they still evident after prolonged hyperglycemia? Are changes reversible after periods of normoglycemia or are changes sustained? Acute changes in cellular metabolism can cause changes in the epigenome by providing more or less substrate for the key histone or DNA modifying enzymes (7). Cells cultured in high glucose-containing medium sustain changes in their histone modification patterns, for example, at the NF-κB locus, that are likely responsible for its sustained increased expression (5, 6, 9). Future studies will be necessary to determine whether the observed changes are reversible or sustained once euglycemic environment is reestablished. The study by Mariappan et al. is significant as it highlights the critical role of hyperinsulinemia in the development of diabetic kidney disease. Indeed, on a cellular level, it is possible that in the setting of both HI and HG, insulin shifts even more glucose into the intracellular compartment providing substrate for the mitochondria and increasing the reactive oxygen species release. Furthermore, the study provides experimental evidence for the notion that acute fluctuations of glucose and insulin levels may be just as damaging to cells as chronic elevated glucose levels (2). For example, in animal models of diabetes, increased reactive oxygen species release and podocyte apoptosis are observed right around the time when hyperglycemia develops and neither of these changes is sustained (10). As we do not routinely treat the hyperglycemia in diabetic mouse models, glucose levels are relatively constant in these animals, which could contribute to the fact that the diabetic mouse models do not develop progressive renal function decline (1). Clinical studies also support the notion that glycemic variability is a critical factor in the development of complications. In summary, this study provides the first description of acute HI/HG-induced kidney damage. In the future, this new model can be used to examine the patho-mechanism of DKD and develop new therapeutic interventions.

Low circulating level of IGF-1 is a distinct indicator for the development of cardiovascular disease caused by combined hyperglycemia and dyslipidemia

Low circulating level of IGF-1 is a distinct indicator for the development of cardiovascular disease caused by combined hyperglycemia and dyslipidemia

Combined acute hyperglycemic and hyperinsulinemic clamp induced profibrotic and proinflammatory responses in the kidney

Increase in matrix protein content in the kidney is a cardinal feature of diabetic kidney disease. While renal matrix protein content is increased by chronic hyperglycemia, whether it is regulated by acute elevation of glucose and insulin has not been addressed. In this study, we aimed to evaluate whether short duration of combined hyperglycemia and hyperinsulinemia, mimicking the metabolic environment of prediabetes and early type 2 diabetes, induces kidney injury. Normal rats were subjected to either saline infusion (control, n = 4) or 7 h of combined hyperglycemic-hyperinsulinemic clamp (HG+HI clamp; n = 6). During the clamp, plasma glucose and plasma insulin were maintained at about 350 mg/dl and 16 ng/ml, respectively. HG+HI clamp increased the expression of renal cortical transforming growth factor-β (TGF-β) and renal matrix proteins, laminin and fibronectin. This was associated with the activation of SMAD3, Akt, mammalian target of rapamycin (mTOR) complexes, and ERK signaling pathways and their downstream target events in the initiation and elongation phases of mRNA translation, an important step in protein synthesis. Additionally, HG+HI clamp provoked renal inflammation as shown by the activation of Toll-like receptor 4 (TLR4) and infiltration of CD68-positive monocytes. Urinary F2t isoprostane excretion, an index of renal oxidant stress, was increased in the HG+HI clamp rats. We conclude that even a short duration of hyperglycemia and hyperinsulinemia contributes to activation of pathways that regulate matrix protein synthesis, inflammation, and oxidative stress in the kidney. This finding could have implications for the control of short-term rises in blood glucose in diabetic individuals at risk of developing kidney disease.

Early Insulin Glycemic Control Combined With tPA Thrombolysis Reduces Acute Brain Tissue Damages in a Focal Embolic Stroke Model of Diabetic Rats

Therapeutic effects of early insulin glycemic control for poststroke hyperglycemia in combination with tissue-type plasminogen activator (tPA) thrombolytic therapy have not yet been studied but are of great clinical interest. In this study, we tested the effects of insulin plus tPA combination in a model of focal embolic stroke in Type I diabetic rats. Streptozotocin was used to produce Type I diabetes in male Wistar rats for 6 weeks and then embolic focal strokes were induced. All rats were treated with insulin or saline at 1 hour followed by tPA or saline at 1.5 hour after stroke. Mortality, infarction, hemispheric swelling, hemorrhagic transformation, and perfusion defects were examined at 24 hours after stroke. Total plasma plasminogen activator inhibitor-1 antigen and activity levels were measured before stroke and 1.5, 3, and 6 hours after stroke by ELISA. Early insulin glycemic control alone or tPA thrombolysis alone had no significant effects on ischemic infarction. However, early insulin glycemic control combined with tPA significantly reduced brain infarction and swelling, ameliorated tPA-associated hemorrhagic transformation, and improved plasma perfusion at 24 hours after stroke. We also found that the combination significantly decreased plasma plasminogen activator inhibitor-1 antigen level at 6 hours and plasminogen activator inhibitor-1 activity at 1.5 and 6 hours after stroke. Early insulin glycemic control may be beneficial in combination with tPA thrombolysis for ischemic stroke with diabetes mellitus or poststroke hyperglycemia.

Alpha-lipoic acid upregulates antioxidant enzyme gene expression and enzymatic activity in diabetic rat kidneys through an O-GlcNAc-dependent mechanism

The combined hyperglycemia lowering and antioxidant actions of α-lipoic acid (LA) contribute to its usefulness in preventing renal injury and other diabetic complications. The precise mechanisms by which LA alters diabetic oxidative renal injury are not known. We hypothesized that LA through its hypoglycemic effect lowers O-GlcNAcylation which influences the expression and activities of antioxidant enzymes which assume important roles in preventing diabetes-induced oxidative renal injury. An experimental model of diabetes was induced in rats by the administration of 40mg/kg streptozotocin (STZ) intraperitoneally (i.p.) for five consecutive days. LA was applied at a dose of 10mg/kg i.p. for 4weeks, starting from the last day of STZ administration. An improved glycemic status of LA-treated diabetic rats was accompanied by a significant suppression of oxidative stress and a reduction of oxidative damage of lipids, proteins and DNA. LA treatment normalized CuZn-superoxide dismutase (SOD) and catalase activities in renal tissue of diabetic rats. These changes were allied with upregulated gene expression and lower levels of O-GlcNA glycosylation. The accompanying increase in MnSOD activity was only linked with upregulated gene expression. The observed antioxidant enzyme gene regulation was accompanied by nuclear translocation of Nuclear factor-erythroid-2-related factor 2 (Nrf2), enhanced expression of heat shock proteins (HSPs) and by reduction in O-GlcNAcylation of HSP90, HSP70, and extracellular regulated kinase and p38. α-Lipoic acid administration activates a coordinated cytoprotective response against diabetes-induced oxidative injury in kidney tissue through an O-GlcNAc-dependent mechanism.