Intermittent high glucose enhances cell growth and collagen synthesis in cultured human tubulointerstitial cells

Glycemic variability leads to higher levels of auto-oxidized oxysterol species in patients with type 1 diabetes mellitus

PURPOSE

Hyperglycemia and glycemic variability (GV) are associated with oxidative stress in patients with diabetes mellitus (DM). Oxysterol species, produced by the non-enzymatic oxidation of cholesterol, are potential biomarkers of oxidative stress. This study examined the relationship between auto-oxidized oxysterols and GV in patients with type 1 DM.

METHODS

Thirty patients with type 1 DM using a continuous subcutaneous insulin infusion pump therapy and a healthy control group (n = 30) were included in this prospective study. A Continuous Glucose Monitoring System device was applied for 72 h. Blood samples were taken for oxysterols produced by non-enzymatic oxidation [7-ketocholesterol (7-KC) and cholestane-3β, 5α, 6β-triol (Chol-Triol)] levels at 72 h. Short-term glycemic variability parameters, mean amplitude of glycemic excursions (MAGE), the standard deviation of glucose measurements (Glucose-SD), and mean of daily differences (MODD) were calculated with continuous glucose monitoring data. HbA1c was used to evaluate glycemic control and HbA1c-SD (the SD of HbA1c over the past year) for long-term glycemic variability.

RESULTS

7-KC and Chol-triol levels were significantly higher in the study group than in the control group. Strong positive correlations were found between 7-KC with MAGE(24-48 h) and Glucose-SD(24-48 h). 7-KC was positively correlated with MAGE(0-72 h) and Glucose-SD(0-72 h). No significant correlation was found between HbA1c and HbA1c -SD with oxysterol levels. The regression models showed that SD(24-48 h) and MAGE(24-48 h) predicted 7-KC levels while HbA1c did not.

CONCLUSIONS

Glycemic variability leads to higher levels of auto-oxidized oxysterol species in patients with type 1 DM independent of long-term glycemic control.

Effect of repeated bolus and continuous glucose infusion on a panel of circulating biomarkers in healthy volunteers

HYPOTHESIS

Glycaemic variability (GV) refers to fluctuations in the blood glucose level and may contribute to complications in patients suffering from Diabetes. Several studies show negative effects of GV on the cardiovascular system, however there is still a lack of conclusive evidence. Using an explorative cardiovascular panel, it is possible to simultaneously measure the effects on proteins relevant for cardiovascular processes. The aim of this study was to investigate the effects of rapid glucose excursions on cardiovascular and metabolic parameters in healthy individuals.

METHODS

An explorative single-blinded cross-over study was performed in ten healthy men. Subjects received 3 times 20 grams of glucose i.v. over 5 minutes or 60 grams of glucose continuously over 3 hours. Blood was taken for repeated measurements of the cardiovascular panel over the following 6 hours and again after 24 and 48 hours.

RESULTS

We observed a significant elevation of 7 cardiovascular biomarkers (BMP6, SLAMF7, LOX-1, ADAMTS13, IL-1RA, IL-4RA, PTX3) at t = 360min after rapid glucose infusion compared to a continuous glucose infusion.

CONCLUSIONS

Intraday GV seems to have acute effects on cardiovascular proteins in healthy test persons. Rapid glucose administration compared to continuous administration showed significant changes in BMP6, SLAMF7, ADAMTS13, IL1RA, PTX3, IL-4RA and LOX-1.

CLINICAL TRIAL REGISTRATION

NCT04488848.

Fasting Glucose Variability as a Risk Indicator for End-Stage Kidney Disease in Patients with Diabetes: A Nationwide Population-Based Study

Given the fact that diabetes remains a leading cause of end-stage kidney disease (ESKD), multi-aspect approaches anticipating the risk for ESKD and timely correction are crucial. We investigated whether fasting glucose variability (FGV) could anticipate the development of ESKD and identify the population prone to the harmful effects of GV. We included 777,192 Koreans with diabetes who had undergone health examinations more than three times in 2005-2010. We evaluated the risk of the first diagnosis of ESKD until 2017, according to the quartile of variability independent of the mean (VIM) of FG using multivariate-adjusted Cox proportional hazards analyses. During the 8-year follow-up, a total of 7290 incidents of ESKD were found. Subjects in the FG VIM quartile 4 had a 27% higher risk for ESKD compared to quartile 1, with adjustment for cardiovascular risk factors and the characteristics of diabetes. This effect was more distinct in patients aged < 65 years; those with a long duration of diabetes; the presence of hypertension or dyslipidemia; and prescribed angiotensin-converting enzyme inhibitors, metformin, sulfonylurea, α-glucosidase inhibitors, and insulin. In contrast, the relationship between baseline FG status and ESKD risk showed a U-shaped association. FGV is an independent risk factor for kidney failure regardless of FG.

Glucose variability predicts 6-month mortality in patients hospitalized with acute heart failure

In diabetes mellitus (DM), glycaemic fluctuations associate with higher oxidative stress than sustained chronic hyperglycaemia and glucose variability increases the risk of chronic diabetic complications. Our hypothesis was that higher glucose variability would associate with mortality after an acute heart failure (HF) episode. We retrospectively analysed patients with DM hospitalized with acute HF between 2009 and 2010. Patients with < 2 point-of-care glucose values/day were excluded. Glucose coefficient of variation (GCV) was defined as (glucose standard deviation/mean glucose) × 100. Patients were categorized according GCV ≤ 30.0 and > 30.0%. Follow-up: 6-months. Endpoint: all-cause mortality. A Cox-regression analysis was used to study the association of glucose variability with 6-month mortality. We studied 214 diabetic patients with acute HF, 49.1% male, mean age 76 years. Mean glycaemia during hospitalization was 187 ± 50 mg/dL, hypoglycaemia (< 70 mg/dL) was reported in 21 patients and mean GCV was 28.3 ± 7.6%. Patients with GCV > 30.0% had higher mean glycaemia, more hypoglycaemic episodes and higher HbA1c; they were also more often treated with insulin. Patients were similar concerning age, gender, comorbidities, left ventricular systolic dysfunction and ischemic heart disease. During the 6-month follow-up, 38 (17.8%) patients died. Patients with GCV > 30.0% had a HR of 6-month mortality of 2.21 (95% CI: 1.16-4.21), p = 0.02. This association with more than twofold higher short-term mortality was independent of main confounders. Elevated glycaemic variability in acute HF admissions of patients with DM predicts short-term mortality. Patients with GCV > 30.0% have an independent more than twofold higher risk of 6-month death after an acute HF hospitalization.

Glucose as a modifiable cause of atherosclerotic cardiovascular disease: Insights from type 1 diabetes and transplantation

Diabetes is a major risk factor for cardiovascular (CV) disease. In contrast to the clear benefits from treatments which reduce blood pressure and lipids, clinical trials targeting blood glucose have not shown clear CV benefits. Interventions to intensify glycemic control early in the course of diabetes may have benefits in long term observational studies (DCCT-EDIC/UKPDS), but may not be helpful if introduced late in the course of type 2 diabetes (ACCORD, ADVANCE, VA-DT). More recent CVOT in high risk subjects suggest that the benefits of SGLT2 and GLP1-RA are glucose-independent. Type 1 diabetes provides a "cleaner" model to study the links between glucose and cardiovascular disease. Abnormalities of glucose regulation in type 1 diabetes is not restricted to hyperglycemia, but includes glycemic variability and hypoglycemia. Increasingly the mechanisms linking glycemic variability and hypoglycemia as key mediators of cardiovascular complications are being understood. Furthermore, data from pancreas and islet transplantation showing reduced cardiovascular mortality and regression of intima-media thickness supports a causal role for glucose in the pathogenesis of atherosclerosis, but suggests that restoration of normal glucose regulation may be required to demonstrate substantial impact on CV risk accrued over decades of type 1 diabetes. Considering the limited organ supply and risks of immunosuppression, advances in biology (stem cell derived beta cells) or technology (automated insulin delivery systems) will be required to provide a scalable solution to deliver optimal glucose control and reduce CV risk for people with type 1 diabetes.

The role of T-cell immunity in COVID-19 severity amongst people living with type II diabetes

The COVID-19 pandemic has highlighted the vulnerability of people with diabetes mellitus (DM) to respiratory viral infections. Despite the short history of COVID-19, various studies have shown that patients with DM are more likely to have increased hospitalisation and mortality rates as compared to patients without. At present, the mechanisms underlying this susceptibility are unclear. However, prior studies show that the course of COVID-19 disease is linked to the efficacy of the host's T-cell responses. Healthy individuals who can elicit a robust T-cell response are more likely to limit the severity of COVID-19. Here, we investigate the hypothesis that an impaired T-cell response in patients with type 2 diabetes mellitus (T2DM) drives the severity of COVID-19 in this patient population. While there is currently a limited amount of information that specifically addresses T-cell responses in COVID-19 patients with T2DM, there is a wealth of evidence from other infectious diseases that T-cell immunity is impaired in patients with T2DM. The reasons for this are likely multifactorial, including the presence of hyperglycaemia, glycaemic variability and metformin use. This review emphasises the need for further research into T-cell responses of COVID-19 patients with T2DM in order to better inform our response to COVID-19 and future disease outbreaks.

Greater daily glucose variability and lower time in range assessed with continuous glucose monitoring are associated with greater aortic stiffness: The Maastricht Study

AIMS

CVD is the main cause of morbidity and mortality in individuals with diabetes. It is currently unclear whether daily glucose variability contributes to CVD. Therefore, we investigated whether glucose variability is associated with arterial measures that are considered important in CVD pathogenesis.

METHODS

We included participants of The Maastricht Study, an observational population-based cohort, who underwent at least 48 h of continuous glucose monitoring (CGM) (n = 853; age: 59.9 ± 8.6 years; 49% women, 23% type 2 diabetes). We studied the cross-sectional associations of two glucose variability indices (CGM-assessed SD [SD_CGM] and CGM-assessed CV [CV_CGM]) and time in range (TIR_CGM) with carotid-femoral pulse wave velocity (cf-PWV), carotid distensibility coefficient, carotid intima-media thickness, ankle-brachial index and circumferential wall stress via multiple linear regression.

RESULTS

Higher SD_CGM was associated with higher cf-PWV after adjusting for demographics, cardiovascular risk factors and lifestyle factors (regression coefficient [B] per 1 mmol/l SD_CGM [and corresponding 95% CI]: 0.413 m/s [0.147, 0.679], p = 0.002). In the model additionally adjusted for CGM-assessed mean sensor glucose (MSG_CGM), SD_CGM and MSG_CGM contributed similarly to cf-PWV (respective standardised regression coefficients [st.βs] and 95% CIs of 0.065 [-0.018, 0.167], p = 0.160; and 0.059 [-0.043, 0.164], p = 0.272). In the fully adjusted models, both higher CV_CGM (B [95% CI] per 10% CV_CGM: 0.303 m/s [0.046, 0.559], p = 0.021) and lower TIR_CGM (B [95% CI] per 10% TIR_CGM: -0.145 m/s [-0.252, -0.038] p = 0.008) were statistically significantly associated with higher cf-PWV. Such consistent associations were not observed for the other arterial measures.

CONCLUSIONS

Our findings show that greater daily glucose variability and lower TIR_CGM are associated with greater aortic stiffness (cf-PWV) but not with other arterial measures. If corroborated in prospective studies, these results support the development of therapeutic agents that target both daily glucose variability and TIR_CGM to prevent CVD.

Glucose Variability: How Does It Work?

A growing body of evidence points to the role of glucose variability (GV) in the development of the microvascular and macrovascular complications of diabetes. In this review, we summarize data on GV-induced biochemical, cellular and molecular events involved in the pathogenesis of diabetic complications. Current data indicate that the deteriorating effect of GV on target organs can be realized through oxidative stress, glycation, chronic low-grade inflammation, endothelial dysfunction, platelet activation, impaired angiogenesis and renal fibrosis. The effects of GV on oxidative stress, inflammation, endothelial dysfunction and hypercoagulability could be aggravated by hypoglycemia, associated with high GV. Oscillating hyperglycemia contributes to beta cell dysfunction, which leads to a further increase in GV and completes the vicious circle. In cells, the GV-induced cytotoxic effect includes mitochondrial dysfunction, endoplasmic reticulum stress and disturbances in autophagic flux, which are accompanied by reduced viability, activation of apoptosis and abnormalities in cell proliferation. These effects are realized through the up- and down-regulation of a large number of genes and the activity of signaling pathways such as PI3K/Akt, NF-κB, MAPK (ERK), JNK and TGF-β/Smad. Epigenetic modifications mediate the postponed effects of glucose fluctuations. The multiple deteriorative effects of GV provide further support for considering it as a therapeutic target in diabetes.

PAR2-Induced Tissue Factor Synthesis by Primary Cultures of Human Kidney Tubular Epithelial Cells Is Modified by Glucose Availability

Coagulopathies common to patients with diabetes and chronic kidney disease (CKD) are not fully understood. Fibrin deposits in the kidney suggest the local presence of clotting factors including tissue factor (TF). In this study, we investigated the effect of glucose availability on the synthesis of TF by cultured human kidney tubular epithelial cells (HTECs) in response to activation of protease-activated receptor 2 (PAR2). PAR2 activation by peptide 2f-LIGRLO-NH₂ (2F, 2 µM) enhanced the synthesis and secretion of active TF (~45 kDa) which was blocked by a PAR2 antagonist (I-191). Treatment with 2F also significantly increased the consumption of glucose from the cell medium and lactate secretion. Culturing HTECs in 25 mM glucose enhanced TF synthesis and secretion over 5 mM glucose, while addition of 5 mM 2-deoxyglucose (2DOG) significantly decreased TF synthesis and reduced its molecular weight (~40 kDa). Blocking glycosylation with tunicamycin also reduced 2F-induced TF synthesis while reducing its molecular weight (~36 kDa). In conclusion, PAR2-induced TF synthesis in HTECs is enhanced by culture in high concentrations of glucose and suppressed by inhibiting either PAR2 activation (I-191), glycolysis (2DOG) or glycosylation (tunicamycin). These results may help explain how elevated concentrations of glucose promote clotting abnormities in diabetic kidney disease. The application of PAR2 antagonists to treat CKD should be investigated further.

Fasting Plasma Glucose Variability and Gastric Cancer Risk in Individuals Without Diabetes Mellitus: A Nationwide Population-Based Cohort Study

Long-term glycemic variability is associated with various adverse health outcomes in patients with diabetes mellitus (DM). However, the relationship between glycemic variability and gastric cancer remains unclear. We aimed to investigate the association between glycemic variability and gastric cancer incidence in individuals without DM.

Glycemic variability and the risk of nonalcoholic fatty liver disease : A nationwide population-based cohort study

AIM

Although few recent studies have reported the association between the glycemic variability and the development of type 2 diabetes mellitus and cardiovascular disease in individuals without diabetes mellitus, the impact of the long-term variability in fasting plasma glucose (FPG) levels on the incident nonalcoholic fatty liver disease (NAFLD) has not been evaluated.

METHODS

The study included 57,636 Korean men and women without NAFLD and diabetes mellitus from the Korean National Health Insurance System cohort. FPG variability was calculated using the coefficient of variation (FPG-CV), standard deviation (FPG-SD), variability independent of the mean (FPG-VIM), and average successive variability (FPG-ASV).

RESULTS

The cumulative incidence of NAFLD demonstrated progressively increasing trends according to the higher quartiles of FPG variability in Kaplan-Meier curves. A multivariable Cox proportional hazard analysis revealed that the hazard ratio for incident NAFLD was 1.15 (95% confidence interval, 1.06-1.24) in the highest quartile of FPG-CV compared with the lowest quartile of FPG-CV after adjusting for various confounding factors, including mean FPG levels. When using FPG-SD, FPG-VIM, and FPG-ASV, the results were similar. The 10-unit increase in FPG variability was associated with a 14% increased risk of NAFLD in the fully adjusted model. Moreover, this effect remained consistent in the subgroup and sensitivity analyses.

CONCLUSION

Increased long-term FPG variability is associated with the development of NAFLD, independent of confounding risk variables including mean FPG levels.

Thresholds of Glycemia and the Outcomes of COVID-19 Complicated With Diabetes: A Retrospective Exploratory Study Using Continuous Glucose Monitoring

OBJECTIVE

Although elevated glucose levels are reported to be associated with adverse outcomes of coronavirus disease 2019 (COVID-19), the optimal range of glucose in patients with COVID-19 and diabetes remains unknown. This study aimed to investigate the threshold of glycemia and its association with the outcomes of COVID-19.

RESEARCH DESIGN AND METHODS

Glucose levels were assessed through intermittently scanned continuous glucose monitoring in 35 patients for an average period of 10.2 days. The percentages of time above range (TAR), time below range (TBR), time in range (TIR), and coefficient of variation (CV) were calculated. Composite adverse outcomes were defined as either the need for admission to the intensive care unit, need for mechanical ventilation, or morbidity with critical illness.

RESULTS

TARs using thresholds from 160 to 200 mg/dL were significantly associated with composite adverse outcomes after adjustment of covariates. Both TBR (<70 mg/dL) and TIR (70-160 mg/dL), but not mean sensor glucose level, were significantly associated with composite adverse outcomes and prolonged hospitalization. The multivariate-adjusted odds ratios of the CV of sensor glucose across tertiles for composite adverse outcomes of COVID-19 were 1.00, 1.18, and 25.2, respectively.

CONCLUSIONS

Patients with diabetes and COVID-19 have an increased risk of adverse outcomes with glucose levels >160 mg/dL and <70 mg/dL and a high CV. Therapies that improve these metrics of glycemic control may result in better prognoses for these patients.

Current concepts and clinical importance of glycemic variability

BACKGROUND AND AIMS

Evolving evidence indicate that variations in blood glucose levels are likely to be an important factor in developing diabetic complications. Monitoring glucose fluctuations in patients remains as a therapeutic challenge and more evidence needs to be created in order to bring GV into limelight. This review encapsulates the most important findings conducted and discusses on them to provide readers a better understanding on this emerging subject.

METHODS

Keyword-based comprehensive desktop search was conducted to gather the relevant literature. Triple-stage cascade type content analysis of the literature was conducted to draw relevant themes of discussions.

RESULTS

High glycemic variability is associated with an increased risk of development of diabetic complications especially in cardiac conditions. The widely used and accepted metrics to determine the variations in blood glucose are Standard deviation (SD), MAGE (Mean amplitude of glycemic excursions) and MODD (Mean of daily differences). Occurrence of blood glucose variations affects at a molecular level thereby causing more harm than the occurrence of hyperglycemia alone.

CONCLUSION

Available data suggest that Glycemic Variability should be used as an additional marker of glycemia. Additional research globally, and in India are required.

Repetitive Intermittent Hyperglycemia Drives the M1 Polarization and Inflammatory Responses in THP-1 Macrophages Through the Mechanism Involving the TLR4-IRF5 Pathway

Repetitive intermittent hyperglycemia (RIH) is an independent risk factor for complications associated with type-2 diabetes (T2D). Glucose fluctuations commonly occur in T2D patients with poor glycemic control or following intensive therapy. Reducing blood glucose as well as glucose fluctuations is critical to the control of T2D and its macro-/microvascular complications. The interferon regulatory factor (IRF)-5 located downstream of the nutrient sensor toll-like receptor (TLR)-4, is emerging as a key metabolic regulator. It remains unclear how glucose fluctuations may alter the IRF5/TLR4 expression and inflammatory responses in monocytes/macrophages. To investigate this, first, we determined IRF5 gene expression by real-time qRT-PCR in the white adipose tissue samples from 39 T2D and 48 nondiabetic individuals. Next, we cultured THP-1 macrophages in hypo- and hyperglycemic conditions and compared, at the protein and transcription levels, the expressions of IRF5, TLR4, and M1/M2 polarization profile and inflammatory markers against control (normoglycemia). Protein expression was assessed using flow cytometry, ELISA, Western blotting, and/or confocal microscopy. IRF5 silencing was achieved by small interfering RNA (siRNA) transfection. The data show that adipose IRF5 gene expression was higher in T2D than nondiabetic counterparts (P = 0.006), which correlated with glycated hemoglobin (HbA1c) (r = 0.47/P < 0.001), homeostatic model assessment of insulin resistance (HOMA-IR) (r = 0.23/P = 0.03), tumor necrosis factor (TNF)-α (r = 0.56/P < 0.0001), interleukin (IL)-1β (r = 0.40/P = 0.0009), and C-C motif chemokine receptor (CCR)-2 (r = 0.49/P < 0.001) expression. IRF5 expression in macrophages was induced/upregulated (P < 0.05) by hypoglycemia (3 mM/L), persistent hyperglycemia (15 mM/L-25 mM/L), and RIH/glucose fluctuations (3-15 mM/L) as compared to normoglycemia (5 mM/L). RIH/glucose fluctuations also induced M1 polarization and an inflammatory profile (CD11c, IL-1β, TNF-α, IL-6, and monocyte chemoattractant protein (MCP)-1) in macrophages. RIH/glucose fluctuations also drove the expression of matrix metalloproteinase (MMP)-9 (P < 0.001), which is a known marker for cardiovascular complication in T2D patients. Notably, all these changes were counteracted by IRF5 silencing in macrophages. In conclusion, RIH/glucose fluctuations promote the M1 polarization and inflammatory responses in macrophages via the mechanism involving TLR4-IRF5 pathway, which may have significance for metabolic inflammation.

Gamma-glutamyl transferase variability and the risk of hospitalisation for heart failure

Objective

Gamma-glutamyl transferase (GGT) is associated with oxidative stress, inflammation, cardiovascular disease and mortality. Variability in metabolic parameters has recently emerged as an indicator of adverse health outcomes, including heart failure (HF).

Methods

We investigated whether GGT variability was associated with the incidence of hospitalisation for heart failure (HHF) in a Korean population without previous HF, ischaemic heart disease or liver disease. This longitudinal cohort study analysed 119 201 individuals from the Korean National Health Insurance Service-National Health Screening Cohort. GGT variability was calculated as the coefficient of variation (CV), SD and variability independent of the mean (VIM).

Results

During the 8.4 years of follow-up, 1387 cases of HHF (1.16%) developed. In the multivariable-adjusted model, the HR of HHF was 1.22 (95% CI 1.05 to 1.42) in the highest quartile of GGT variability compared with the lowest quartile, as assessed by CV after adjusting for confounding factors, including alcohol consumption and mean GGT levels. Consistent results were obtained using other indices of GGT variability such as SD (HR 1.37, 95% CI 1.16 to 1.62) and VIM (HR 1.29, 95% CI 1.11 to 1.50). In a subgroup analysis stratified by risk factor variables, although a similar relationship was observed, it was more prominent in individuals with dyslipidaemia.

Conclusions

The results of the present study demonstrated that variability in GGT was independently associated with the incidence of HHF. These findings suggest that higher GGT variability may be useful as an indicator of future risk of HF.

Association of fasting plasma glucose variability with gestational diabetes mellitus: a nationwide population-based cohort study

OBJECTIVE

Long-term glycemic variability has recently been recognized as another risk factor for future adverse health outcomes. We aimed to evaluate the risk of gestational diabetes mellitus (GDM) according to the prepregnancy long-term fasting plasma glucose (FPG) variability.

RESEARCH DESIGN AND METHODS

A total of 164 053 women who delivered their first baby between January 1, 2012 and December 31, 2015, were selected from the Korean National Health Insurance data. All women underwent at least three national health screening examinations, and the last examination should be conducted within 2 years before their first delivery. GDM was defined as the presence of more than four times of claim of GDM (International Classification of Disease, 10th Revision (ICD-10) O24.4 and O24.9) or prescription of insulin under the ICD-code of GDM. FPG variability was assessed by variability independent of the mean (FPG-VIM), coefficient of variation, SD, and average successive variability.

RESULTS

Among the 164 053 women, GDM developed in 6627 (4.04%). Those in the higher quartiles of FPG-VIM showed a stepwise increased risk of GDM. In fully adjusted model, the ORs for GDM was 1.22 (95% CI 1.14 to 1.31) in women with the highest FPG-VIM quartile compared with those in the lowest quartile. The risk for GDM requiring insulin therapy was 48% increase in women in the highest quartile of FPG-VIM compared with those in the lowest quartile, while that for GDM not requiring insulin therapy was 19% increase. The association between high FPG variability and the risk of GDM was intensified in the obese and aged more than 35 years women.

CONCLUSIONS

Increased FPG variability in the prepregnancy state is associated with the risk of GDM independent of confounding factors. Therefore, prepregnancy FPG variability might be a surrogate marker of the risk of GDM.

Association of Glycemic Indices (Hyperglycemia, Glucose Variability, and Hypoglycemia) with Oxidative Stress and Diabetic Complications

Oxidative stress (OS) is defined as a disturbance in the prooxidant-antioxidant balance of the cell, in favor of the former, which results in the antioxidant capacity of the cell to be overpowered. Excess reactive oxygen species (ROS) production is very harmful to cell constituents, especially proteins, lipids, and DNA, thus causing damage to the cell. Oxidative stress has been associated with a variety of pathologic conditions, including diabetes mellitus (DM), cancer, atherosclerosis, neurodegenerative diseases, rheumatoid arthritis, ischemia/reperfusion injury, obstructive sleep apnea, and accelerated aging. Regarding DM specifically, previous experimental and clinical studies have pointed to the fact that oxidative stress probably plays a major role in the pathogenesis and development of diabetic complications. It is postulated that hyperglycemia induces free radicals and impairs endogenous antioxidant defense systems through several different mechanisms. In particular, hyperglycemia promotes the creation of advanced glycation end-products (AGEs), the activation of protein kinase C (PKC), and the hyperactivity of hexosamine and sorbitol pathways, leading to the development of insulin resistance, impaired insulin secretion, and endothelial dysfunction, by inducing excessive ROS production and OS. Furthermore, glucose variability has been associated with OS as well, and recent evidence suggests that also hypoglycemia may be playing an important role in favoring diabetic vascular complications through OS, inflammation, prothrombotic events, and endothelial dysfunction. The association of these diabetic parameters (i.e., hyperglycemia, glucose variability, and hypoglycemia) with oxidative stress will be reviewed here.

Glycaemic variability: The under-recognized therapeutic target in type 1 diabetes care

Type 1 diabetes mellitus (T1DM) remains one of the most challenging long-term conditions to manage. Despite robust evidence to demonstrate that near normoglycaemia minimizes, but does not completely eliminate, the risk of complications, its achievement has proved almost impossible in a real-world setting. HbA1c to date has been used as the gold standard marker of glucose control and has been shown to reflect directly the risk of diabetes complications. However, it has been recognized that HbA1c is a crude marker of glucose control. Continuous glucose monitoring (CGM) provides the ability to measure and observe inter- and intraday glycaemic variability (GV), a more meaningful measure of glycaemic control, more relevant to daily living for those with T1DM. This paper reviews the relationship between GV and hypoglycaemia, and micro- and macrovascular complications. It also explores the impact on GV of CGM, insulin pumps, closed-loop technologies, and newer insulins and adjunctive therapies. Looking to the future, there is an argument that GV should become a key determinant of therapeutic success. Further studies are required to investigate the pathological and psychological benefits of reducing GV.

Effects of Variability in Blood Pressure, Glucose, and Cholesterol Concentrations, and Body Mass Index on End-Stage Renal Disease in the General Population of Korea

Aim: Metabolic parameters, such as blood pressure, glucose, lipid levels, and body weight, can interact with each other, and this clustering of metabolic risk factors is related to the progression to end-stage renal disease (ESRD). The effect of variability in metabolic parameters on the risk of ESRD has not been studied previously. Methods: Using nationally representative data from the Korean National Health Insurance System, 8,199,135 participants who had undergone three or more health examinations between 2005 and 2012 were included in this analysis. Intraindividual variability in systolic blood pressure (SBP), fasting blood glucose (FBG), total cholesterol (TC), and body mass index (BMI) was assessed by examining the coefficient of variation, variability independent of the mean, and average real variability. High variability was defined as the highest quartile of variability and low variability was defined as the lower three quartiles of variability. Results: Over a median (5–95%) of 7.1 (6.5–7.5) years of follow-up after the variability assessment period, 13,600 (1.7/1000 person-years) participants developed ESRD. For each metabolic parameter, an incrementally higher risk of ESRD was observed for higher variability quartiles compared with the lowest quartile. The risk of ESRD was 46% higher in the highest quartile of SBP variability, 47% higher in the highest quartile of FBG variability, 56% higher in the highest quartile of BMI variability, and 108% higher in the highest quartile of TC variability. Compared with the group with low variability for all four parameters, the group with high variability for all four parameters had a significantly higher risk for incident ESRD (hazard ratio (HR) 4.12; 95% CI 3.72–4.57). Conclusions: Variability in each metabolic parameter was an independent predictor of the development of ESRD among the general population. There was a composite effect of the variability in additional metabolic parameters on the risk of ESRD.

Glycaemic variability in diabetes: clinical and therapeutic implications

Glycaemic variability is an integral component of glucose homoeostasis. Although it has not yet been definitively confirmed as an independent risk factor for diabetes complications, glycaemic variability can represent the presence of excess glycaemic excursions and, consequently, the risk of hyperglycaemia or hypoglycaemia. Glycaemic variability is currently defined by a large and increasing number of metrics, representing either short-term (within-day and between-day variability) or long-term glycaemic variability, which is usually based on serial measurements of HbA_1c or other measures of glycaemia over a longer period of time. In this Review, we discuss recent evidence examining the association between glycaemic variability and diabetes-related complications, as well as non-pharmacological and pharmacological strategies currently available to address this challenging aspect of diabetes management.

Diabetes and Vascular Disease: Is It All About Glycemia?

BACKGROUND

Diabetes is increasing over time, mainly driven by obesity, aging, and urbanization. Classical macro- and microvascular complications represent the final result of a complex interplay involving atherosclerosis at all stages.

METHODS

In this review, we aim at focusing on current updates in the pathophysiology of vascular disease in diabetes and discussing how new therapies might influence the management of these patients at high cardiovascular risk. Diabetes shows accelerated atherosclerosis with a larger inflammatory cell infiltrate, thus favoring the development of heart failure. 'Diabetic cardiomyopathy' perfectly describes a specific ischemia- and hypertension- independent entity due to diabetes-related metabolic alterations on myocardial function. Moreover, platelets from subjects with diabetes display a typical hyperreactivity explaining the stronger adhesion, activation, and aggregation. Additionally, diabetes provokes an exaggerated stimulation of the endothelium, with an increased release of reactive oxygen species and a reduced release of nitric oxide, both key elements of the endothelial dysfunction. Also, the coagulation cascade and leukocytes activate contributing to this pro-thrombotic environment. Neutrophils have been recently recognized to play a pivotal role by releasing neutrophil extracellular traps. Finally, microparticles from platelets, neutrophils or monocytes are detrimental effectors on the vessel wall and are involved both in vascular dysfunction and in thrombotic complications.

CONCLUSION

In light of these findings, the therapeutic management of diabetes needs to be mostly focused on limiting the progression of complications by targeting precise pathophysiological mechanisms rather than the mere glycemic control, which failed to markedly reduce the risk for macrovascular complications and mortality.

Association of HbA1C Variability and Renal Progression in Patients with Type 2 Diabetes with Chronic Kidney Disease Stages 3⁻4

Little is known about the predictive value of glycosylated hemoglobin (HbA_1C) variability in patients with advanced chronic kidney disease (CKD). The aim of this study was to investigate whether HbA_1C variability is associated with progression to end-stage renal disease in diabetic patients with stages 3–5 CKD, and whether different stages of CKD affect these associations. Three hundred and eighty-eight patients with diabetes and stages 3–5 CKD were enrolled in this longitudinal study. Intra-individual HbA_1C variability was defined as the standard deviation (SD) of HbA_1C, and the renal endpoint was defined as commencing dialysis. The results indicated that, during a median follow-up period of 3.5 years, 108 patients started dialysis. Adjusted Cox analysis showed an association between the highest tertile of HbA_1C SD (tertile 3 vs. tertile 1) and a lower risk of the renal endpoint (hazard ratio = 0.175; 95% confidence interval = 0.059–0.518; p = 0.002) in the patients with an HbA_1C level ≥ 7% and stages 3–4 CKD, but not in stage 5 CKD. Further subgroup analysis showed that the highest two tertiles of HbA_1C SD were associated with a lower risk of the renal endpoint in the group with a decreasing trend of HbA_1C. Our results demonstrated that greater HbA_1C variability and a decreasing trend of HbA_1C, which may be related to intensive diabetes control, was associated with a lower risk of progression to dialysis in the patients with stages 3–4 CKD and poor glycemic control (HbA1c ≥ 7%).

Unraveling reno-protective effects of SGLT2 inhibition in human proximal tubular cells

Large clinical trials demonstrated that SGLT2 inhibitors (SGLT2i) slow the progression of kidney function decline in type 2 diabetes. Because the underlying molecular mechanisms are largely unknown, we studied the effects of SGLT2i on gene expression in two human proximal tubular (PT) cell lines under normoglycemic conditions, utilizing two SGLT2i, namely empagliflocin and canagliflocin. Genome-wide expression analysis did not reveal substantial differences between these two SGLT2i. Microarray hybridization analysis identified 94 genes that were both upregulated by TGF-β1 and downregulated by either of the two SGLT2i in HK-2 and RPTEC/TERT1 (renal proximal tubular epithelial cells/telomerase reverse transcriptase 1) cells. Extracellular matrix organization showed the highest significance in pathway enrichment analysis. Differential gene expression of three annotated genes of interest within this pathway was verified on mRNA level in both cell lines. Whereas TGF-β1 induced mRNA expression of thrombospondin 1 (THBS1; 4.3-fold), tenascin C (TNC; 8-fold), and platelet-derived growth factor subunit B (PDGF-B; 4.2-fold), SGLT2i downregulated basal mRNA expression of THBS1 (0.2-fold), TNC (0.5 fold), and PDGF-B (0.6-fold). Administration of SGLT2i in the presence of TGF-β1 resulted in a significant inhibition of TGF-β1-induced THBS1 and TNC mRNA expression and TGF-β1-induced THBS1, TNC, and PDGF-BB protein expression. We conclude that SGLT2i block basal and TGF-β1-induced expression of key mediators of renal fibrosis and kidney disease progression in two independent human PT cell lines.

Diabetes mellitus and abdominal aortic aneurysms: A review of the mechanisms underlying the negative relationship

INTRODUCTION

Diabetes mellitus appears to be negatively associated with abdominal aortic aneurysm; however, the mechanisms underlying this relationship remain poorly understood. The aim of this article is to provide a comprehensive review of the currently understood biological pathways underlying this relationship.

METHODS

A review of the literature ('diabetes' OR 'hyperglycaemia' AND 'aneurysm') was performed and relevant studies grouped into biological pathways.

RESULTS

This review identified a number of biological pathways through which diabetes mellitus may limit the presence, growth and rupture of abdominal aortic aneurysms. These include those influencing extracellular matrix volume, extracellular matrix glycation, the formation of advanced glycation end-products, inflammation, oxidative stress and intraluminal thrombus biology. In addition, there is an increasing evidence to suggest that the medications used to treat diabetes can also limit the development and progression of abdominal aortic aneurysms.

CONCLUSION

The negative association between diabetes and abdominal aortic aneurysm is robust. Future studies should attempt to target the pathways identified in this review to develop novel therapeutic agents aimed at slowing or even halting aneurysm progression.

Kidney atrophy vs hypertrophy in diabetes: which cells are involved?

One of the first structural changes in diabetic nephropathy (DN) is the renal enlargement. These changes resulted in renal hypertrophy in both glomerular and tubular cells. Shrink in the kidney size, which described as kidney atrophy resulted from the loss of nephrons or abnormal nephron function and lead to loss of the kidney function. On the other hand, increase in kidney size, which described as hypertrophy resulted from increase in proximal tubular epithelial and glomerular cells size. However overtime, tubular atrophy and tubulointerstitial fibrosis occurs as subsequent changes in tubular cell hypertrophy, which is associated with the infiltration of fibroblast cells into the tubulointerstitial space. The rate of deterioration of kidney function shows a strong correlation with the degree of tubulointerstitial fibrosis. A consequence of long-standing diabetes/hyperglycemia may lead to major changes in renal structure that occur but not specific only to nephropathy. Identifying type of cells that involves in renal atrophy and hypertrophy may help to find a therapeutic target to treat diabetic nephropathy. In summary, the early changes in diabetic kidney are mainly includes the increase in tubular basement membrane thickening which lead to renal hypertrophy. On the other hand, only renal tubule is subjected to apoptosis, which is one of the characteristic morphologic changes in diabetic kidney to form tubular atrophy at the late stage of diabetes.

Role of CHA2DS2-VASc score in predicting new-onset atrial fibrillation in patients with type 2 diabetes mellitus with and without hyperosmolar hyperglycaemic state: real-world data from a nationwide cohort

PURPOSE

The objective of the current study was to explore the role of CHA₂DS₂-VASc score in predicting incidence of atrial fibrillation (AF) in patients with type 2 diabetes mellitus (DM). Furthermore, the use of the CHA₂DS₂-VASc score for stratifying new-onset AF risk in patients with DM and with/without hyperosmolar hyperglycaemic state (HHS) was also compared.

METHODS

The study subjects were identified from Longitudinal Health Insurance Database provided by the National Health Research Institutes. The patients with DM were divided into two groups based on a history of HHS or not. The predictive ability of CHA₂DS₂-VASc score for stratifying new-onset AF risk in the two groups was calculated using the area under the curve of receiver-operating characteristic (AUROC).

RESULTS

The present study involved a total of 69 530 patients with type 2 DM. Among them, 1558 patients had a history of HHS, whereas 67 972 patients did not. The AUROC of the CHA₂DS₂-VASc score as a predictor of incident AF in patients with DM and with/without HHS was 0.67 (95% CI 0.59 to 0.75) and 0.71 (95% CI 0.70 to 0.72), respectively.

CONCLUSIONS

To conclude, we reported for the first time on the assessment of CHA₂DS₂-VASc score for incident AF risk discrimination in patients with type 2 DM. We further found that the predictive ability of the CHA₂DS₂-VASc score was attenuated in patients with type 2 DM and with HHS in comparison with those without HHS.

A review of glucagon-like peptide-1 receptor agonists and their effects on lowering postprandial plasma glucose and cardiovascular outcomes in the treatment of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is an independent risk factor for cardiovascular (CV) comorbidities, with CV disease being the most common cause of death in adults with T2DM. Although glucocentric therapies may improve glycaemic control (as determined by glycated haemoglobin levels), evidence suggests that this approach alone has limited beneficial effects on CV outcomes relative to improvements in lipid and blood pressure control. This may be explained in part by the fact that current antidiabetic treatment regimens primarily address overall glycaemia and/or fasting plasma glucose, but not the postprandial plasma glucose (PPG) excursions that have a fundamental causative role in increasing CV risk. This literature review evaluates the relationship between PPG and the risk of CV disease, discusses the treatment of T2DM with glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and examines the associated CV outcomes. The literature analysis suggests that exaggerated PPG excursions are a risk factor for CV disease because of their adverse pathophysiologic effects on the vasculature, resulting in increased all-cause and CV-related mortality. Although GLP-1 RAs are well established in the current T2DM treatment paradigm, a subgroup of these compounds has a particularly pronounced, persistent and short-lived effect on gastric emptying and, hence, lower PPG substantially. However, current long-term data on CV outcomes with GLP-1 RAs are contradictory, with both beneficial and adverse effects having been reported. This review explores the opportunity to direct treatment towards controlling PPG excursions, thereby improving not only overall glycaemic control but also CV outcomes.

Uncoupling Protein 2 Inhibition Exacerbates Glucose Fluctuation-Mediated Neuronal Effects

Though glucose fluctuations have been considered as an adverse factor for the development of several diabetes-related complications, their impact in the central nervous system is still not fully elucidated. This study was conducted to evaluate the responses of neuronal cells to different glycemic exposures alongside to elucidate the role of uncoupling protein 2 (UCP2) in regulating such responses. To achieve our goals, primary cortical neurons were submitted to constant high (HG)/low (LG) or glucose level variations (GVs), and the pharmacological inhibition of UCP2 activity was performed using genipin. Results obtained show that GV decreased neuronal cells' viability, mitochondrial membrane potential, and manganese superoxide dismutase activity and increased reactive oxygen species (ROS) production. GV also caused an increase in the glutathione/glutathione disulfide ratio and in the protein expression levels of nuclear factor E2-related factor 2 (NRF2), UCP2, NADH-ubiquinone oxidoreductase chain 1 (ND1), and mitochondrially encoded cytochrome c oxidase I (MTCO1), both mitochondrial DNA encoded subunits of the electron transport chain. Contrariwise, genipin abrogated all those compensations and increased the levels of caspase 3-like activity, potentiated mitochondrial ROS levels, and the loss of neuronal synaptic integrity, decreased the protein expression levels of NRF1, and increased the protein expression levels of UCP5. Further, in the control and LG conditions, genipin increased mitochondrial ROS and the protein expression levels of UCP4, postsynaptic density protein 95 (PSD95), ND1, and MTCO1. Overall, these observations suggest that UCP2 is in the core of neuronal cell protection and/or adaptation against GV-mediated effects and that other isoforms of neuronal UCPs can be upregulated to compensate the inhibition of UCP2 activity.

Assessment of Different Transfection Parameters in Efficiency Optimization

Achieving optimal transfection efficiency is the most critical step in overcoming the primary obstacle to success in nonviral-mediated gene therapy. Several transfection parameters were being examined including the effects of different types of transfection media, glucose concentration, reporter DNA concentration, and incubation time in lipotransfectant. Efficiency of transfection obtained was highest for Opti-MEM I (29 ± 2.28%; p = 0.001) followed by M199 (24 ± 1.54%; p = 0.009), both of which performed significantly better than DMEM (14 ± 0.28%) as a transfection medium. The rate of transfection was affected by glucose levels in only DMEM with higher efficiency achieved using low glucose containing DMEM (17 ± 0.38%) than its counterpart. Furthermore, transfection rate and cell viability were severely hampered by lengthened exposure to transfection complexes, leading to an overall mean efficiency of 5 ± 0.87%. However, doubling the DNA content in the transfection mixture did not significantly change the mean rate of transfection in M199 medium (24 ± 1.54% to 27 ± 1.54%; p = 0.273). The overall range of mean efficiency acquired with our protocol under different transfection conditions was between 14% and 29%. Hopefully results from this study will further potential success in nonviral-mediated gene transfer.

Impact of a Paper-Based Dynamic Insulin Infusion Protocol on Glycemic Variability, Time in Target, and Hypoglycemic Risk: A Stepped Wedge Trial in Medical Intensive Care Unit Patients

BACKGROUND

Stress-induced hyperglycemia is a common feature of intensive care unit (ICU) patients. Besides mean blood glucose (BG) level, glucose variability and hypoglycemia have been highlighted as independent predictors of ICU and hospital mortality. Recent ICU recommendations suggest using insulin infusion protocols that can minimize glucose variability and hypoglycemic risk. Our aim was to assess the efficacy, safety, and acceptance by nurses of a paper-based simple dynamic insulin protocol compared with those by nurses of a paper-based static protocol.

METHODS

This is a 1 year stepped-wedge study that compared a static sliding scale protocol (SP - static protocol) with a validated dynamic paper-based intravenous insulin infusion protocol (DP - dynamic protocol) in medical ICU patients of a single university hospital. Patients with stress-induced hyperglycemia >9.9 mmol/L and ≥48 h intravenous insulin infusion were included in this trial.

RESULTS

One hundred thirty-one patients were included and received continuous intravenous insulin infusion managed with SP (n = 65) or DP (n = 66). Glucose variability was significantly higher in the SP group than in the DP group (mean average glucose excursion index: 0.90 [0.00-1.91] mmol/L vs. 0.00 [0.00-0.90] mmol/L, respectively; P = 0.001). The percentage of time spent in the target range (7.7-9.9 mmol/L) was lower in the SP group than in the DP group (42.5% [28.8%-54.2%] vs. 47.5% [36.6%-57.1%]; P = 0.037). Low BG (<4.4 mmol/L) and hypoglycemia (<3.3 mmol/L) were more frequent in the SP group than in the DP group. According to a satisfaction survey, this protocol was well accepted by nurses.

CONCLUSIONS

Our simple and feasible paper-based, dynamic insulin infusion protocol reduced glycemic variability and hypoglycemic risk in a medical ICU.

Blood glucose fluctuation accelerates renal injury involved to inhibit the AKT signaling pathway in diabetic rats

Blood glucose fluctuation is associated with diabetic nephropathy. However, the mechanism by which blood glucose fluctuation accelerates renal injury is not fully understood. The aim of the present study was to assess the effects of blood glucose fluctuation on diabetic nephropathy in rats and investigate its underlying mechanism. Diabetes in the rats was induced by a high sugar, high-fat diet, and a single dose of STZ (35 mg/kg)-injected intraperitoneally. Unstable blood sugar models were induced by subcutaneous insulin injection and intravenous glucose injection alternately. Body weight, glycosylated hemoglobin A1c (HbAlc), blood urea nitrogen (BUN), serum creatinine (Scr), and Creatinine clearance (Ccr) were assessed. T-SOD activity and MDA level were measured by assay kit. Change in renal tissue ultrastructure was observed by light microscopy and electron microscopy. Phosphorylated ser/thr protein kinase (p-AKT) (phosphor-Ser473), phosphorylated glycogen synthase kinase-3 beta (p-GSK-3β) (phosphor-Ser9), Bcl-2-associated X protein (BAX), B cell lymphoma/leukemia 2 (BCL-2), and cleaved-cysteinyl aspartate-specific proteinase-3 (caspase-3) levels were detected by immunohistochemistry and Western blot. We observed that BUN and Scr were increased in diabetic rats, and Ccr was decreased. Furthermore, blood glucose fluctuations could exacerbate the Ccr changes. Renal tissue ultrastructure was also seriously injured by glucose variability in diabetic rats. In addition, glucose fluctuation increased the oxidative stress of renal tissue. Moreover, fluctuating blood glucose decreased p-AKT level and BCL-2, and increased p-GSK-3β, BAX, cleaved-caspase-3 levels, and ratio of BAX/BCL-2 in the kidneys of diabetic rats. In conclusion, these results suggest that blood glucose fluctuation accelerated renal injury is due, at least in part to its oxidative stress promoting and inhibiting the AKT signaling pathway in diabetic rats.

Effect of glucose variability on pathways associated with glucotoxicity in diabetes: Evaluation of a novel in vitro experimental approach

AIMS

Glycaemic variability (GV) has been hypothesized to increase the risk of diabetes complications; however, results of clinical studies are contradictory. The effect of GV on cell phenotypes has been investigated in vitro showing that GV may have more deleterious effect on cells that high glucose itself. However, methodology used to study GV in vitro differs significantly between studies and does not reflect in vivo situation. Therefore we aimed to establish clinically relevant an in vitro experimental approach for the study of GV that reflects intra-day glucose fluctuations of subjects with type 1 diabetes mellitus (T1DM) and of healthy subjects and to test how low and high GV affect expression of genes that protects cells from hyperglycaemia-induced damage.

METHODS

Human umbilical vein endothelial cells (HUVEC) were cultured 24h in medium with different glucose profiles: high GV, low GV and GV of healthy subjects-profiles created according to CGM of T1DM patients and healthy subjects. These profiles were compared to commonly used 5.5 and 25mmol/l glucose concentrations. Gene expression was determined using quantitative PCR.

RESULTS

Our results showed general down-regulation of enzymes that are involved in the protection against hyperglycaemia-induced intracellular changes in both low and high GV compared to normal glycaemia similarly to the decrease induced by continuous hyperglycaemia. Gene expressions did not differ between high and low GV.

CONCLUSION

Our data indicate that GV may have similar or even greater effect than continuous hyperglycaemia on the expression of several genes relevant to pathogenesis of diabetes microvascular complications.

Fasting Glucose is a Useful Indicator for Cerebrovascular Risk in Non-Diabetic Koreans: Association With Oxidative Stress and Inflammation

Diabetes and impaired fasting glucose are associated with incidence of cerebro-/cardio-vascular diseases. This study hypothesized that fasting glycemic status may reflect cerebrovascular risk in non-diabetic Koreans. Fasting glycemic status, lipid profiles, oxidative stress, and inflammation markers were measured in non-diabetic subjects (healthy controls, n = 112 and stroke n = 41). Systolic blood pressure, fasting glucose, glycated hemoglobin (HbA1C), triglycerides, high sensitivity C-reactive protein (hs-CPR), interleukin-6, and tumor necrosis factor-alpha were higher, and high density lipoprotein (HDL)-cholesterols were lower in patients with stroke than healthy controls. Fasting glucose positively correlated with hs-CRP, interleukin-6, tumor necrosis factor-alpha, oxidized low density lipoprotein (LDL) and malondialdehyde. The significances continued or at least turned to a trend after adjustments for confounding factors. Multiple regression analyses revealed that fasting glucose was mainly associated with cerebrovascular risk (β'-coefficient = 0.284, p < 0.0001) together with age, systolic blood pressure, total cholesterol, hs-CRP, body mass index, dietary poly unsaturated fatty acid/saturated fatty acid (PUFA/SFA), and HbA1C (r² = 0.634, p = 0.044). The subjects were subdivided by their fasting glucose levels [normal fasting glucose: 70-99 mg/dL, n = 91 [NFG-control] and n = 27 [NFG-stroke]; higher fasting glucose: 100-125 mg/dL, n = 21 [HFG-control] and n = 14 [HFG-stroke]). In both controls and stroke patients, HFG groups show higher triglyceride, total- and LDL-cholesterol and lower HDL-cholesterol than NFG groups. Control-HFG group showed significantly higher levels of oxidative stress and inflammation than control-NFG group. Stroke-HFG group also showed significantly higher inflammatory levels than stroke-NFG group, moreover the highest among the groups. Additionally, stroke-NFG group consumed higher PUFA/SFA than stroke-HFG group. Fasting glucose may be a useful indicator for cerebrovascular risk in non-diabetic individuals which may be mediated by oxidative stress and inflammation status.

Visit-to-Visit Glucose Variability Predicts the Development of End-Stage Renal Disease in Type 2 Diabetes: 10-Year Follow-Up of Taiwan Diabetes Study

The purpose of this study was to examine the association of glucose variability using coefficient of variation of fasting plasma glucose (FPG-CV) and coefficient of variation of glycated hemoglobin (HbA1c-CV) to end-stage renal disease (ESRD) in 31,841 Chinese patients with type 2 diabetes.Patients with type 2 diabetes enrolled in National Diabetes Care Management Program, aged ≧30 years, and free of ESRD (n = 31,841) in January 1, 2002 to December 31, 2004 were included. Extended Cox proportional hazards regression models with competing risk of all-cause mortality were used to evaluate risk factors on ESRD incidence. Patients were followed till 2012.After a median follow-up period of 8.23 years, 1642 patients developed ESRD, giving a crude incidence rate of 6.27/1000 person-years (6.36 for men, 6.19 for women). After the multivariate adjustment, both FPG-CV and HbA1c-CV were independent predictors of ESRD with corresponding hazard ratios of 1.20 (95% confidence interval [CI] 1.01, 1.41), 1.24 (95% CI 1.05, 1.46) in HbA1c-CV from fourth to fifth quintile and 1.23 (95% CI 1.03, 1.47) in FPG-CV from fifth quintile.One-year visit-to-visit glucose variability expressed by FPG-CV and HbA1c-CV predicted development of ESRD in patients with type 2 diabetes, suggesting therapeutic strategies toward a goal to minimize glucose fluctuation.

Accumulation of γ-aminobutyric acid by Enterococcus avium 9184 in scallop solution in a two-stage fermentation strategy

In this study, a new bacterial strain having a high ability to produce γ‐aminobutyric acid (GABA) was isolated from naturally fermented scallop solution and was identified as Enterococcus avium. To the best of our knowledge, this is the first study to prove that E. avium possesses glutamate decarboxylase activity. The strain was then mutagenized with UV radiation and was designated as E. avium 9184. Scallop solution was used as the culture medium to produce GABA. A two‐stage fermentation strategy was applied to accumulate GABA. In the first stage, cell growth was regulated. Optimum conditions for cell growth were pH, 6.5; temperature, 37°C; and glucose concentration, 10 g·L⁻¹. This produced a maximum dry cell mass of 2.10 g·L⁻¹. In the second stage, GABA formation was regulated. GABA concentration reached 3.71 g·L⁻¹ at 96 h pH 6.0, 37°C and initial l‐monosodium glutamate concentration of 10 g·L⁻¹. Thus, compared with traditional one‐stage fermentation, the two‐stage fermentation significantly increased GABA accumulation. These results provide preliminary data to produce GABA using E. avium and also provide a new approach to process and utilize shellfish.

Novel mechanism of transcriptional regulation of cell matrix protein through CREB

The transcription mechanism(s) of renal cell matrix accumulation in diabetes does not explored. Phosphorylation of the transcription factor cAMP-responsive element binding protein (CREB) significantly increased in cells treated with high glucose (HG) compared to cell grown in normal glucose (NG). Cells pretreated with rapamycin before exposure to HG showed significant decrease phosphorylation of CREB, increase in AMPK activity and decrease protein/mRNA and promoter activity of fibronectin. In addition, cells transfected with siRNA against CREB showed significant increase in AMPK activity, decrease in protein/mRNA and promoter activity of fibronectin. Cells treated with HG showed nuclear localization of p-CREB while pretreated cells with rapamycin reversed HG effect. Moreover, gel shift analysis shows increase binding of CREB to fibronectin promoter in cells treated with HG while cells pretreated with rapamycin reversed the effect of HG. Furthermore, db/db mice treated with rapamycin showed significant increase in AMPK activity, decrease in expression of p-CREB and protein/mRNA of fibronectin. Strong staining of fibronectin and p-CREB was detected in kidney cortex of db/db mice while treated mice with rapamycin reversed hyperglycemia effect. In summary, our data provide a novel mechanism of transcriptional regulation of fibronectin through CREB that may be used as therapeutic approach to prevent diabetes complications.

Glycemic variability in nondiabetic morbidly obese persons: results of an observational study and review of the literature

Glycemic variability (GV) is correlated with oxidative stress which may lead to increased cardiovascular risk and poor clinical outcomes in people with prediabetes and diabetes. We sought to understand whether morbidly obese persons without diabetes by standard criteria have dysglycemia as measured by GV. We performed an observational study of GV metrics and carotid intima media thickness (CIMT) in 21 morbidly obese normoglycemic and 15 morbidly obese prediabetic applicants to The Biggest Loser television show. The results were compared to previously published studies in normoglycemic nonobese and obese individuals. Glucose was measured with a masked continuous glucose monitor (CGM) over 3 to 8 days and carotid intima media thickness (CIMT) was determined by ultrasound. CGM-derived GV metrics for GV were coefficient of variation (CV), standard deviation (SD), mean amplitude of glycemic excursions (MAGE), continuous overall net glycemic action-1 hour (CONGA1), and mean of daily differences (MODD). We found that morbidly obese subjects (n = 21) who were normoglycemic by standard criteria had higher GV (CV = 22%, SD = 24.2 mg/dl and MAGE = 48.6 mg/dl) than previous reports of normoglycemic, nonobese individuals (CV = 12-18%, SD = 11.5-15.0 mg/dl, and MAGE = 26.3-28.3 mg/dl). Morbidly obese prediabetic subjects (n = 15) had GV metrics indistinguishable from those morbidly obese subjects who were normoglycemic. CIMT was higher in both morbidly obese groups compared with historical age- and sex-matched controls. Normoglycemic and prediabetic morbidly obese individuals have higher GV compared with normal weight, nondiabetic individuals. We speculate that this may increase the risk for macrovascular disease through excessive oxidative stress.

Comparison of repaglinide and metformin monotherapy as an initial therapy in Chinese patients with newly diagnosed type 2 diabetes mellitus

BACKGROUND

We aimed to compare the effect of repaglinide and metformin monotherapy as an initial therapy in Chinese patients with newly diagnosed type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

In this 15-week, open-labelled, parallel-controlled, randomised study, 60 Chinese drug-naive patients with newly diagnosed T2DM were randomised (2:1) to receive repaglinide or metformin monotherapy. Primary endpoint was change in HbA1c from baseline to the end of the trial. Secondary endpoints included changes in glycaemic variability, insulin sensitivity and β-cell function.

RESULTS

Patients in both repaglinide and metformin groups achieved significant reductions in HbA1c (-1.8 ± 1.5 vs -1.6 ± 1.5%), FPG (fasting blood glucose) (-1.7 ± 1.7 vs -2.1 ± 1.7  mmol/l) and 2-h PPG (post-prandial glucose) (-3.8 ± 3.1 vs -3.8 ± 3.6  mmol/l), with no statistical differences between the groups. Glycaemic variability, glucose infusion rate and β-cell function were all significantly improved from baseline in the two groups (all P<0.05), without any statistical differences in the improvement between the groups.

CONCLUSIONS

Repaglinide and metformin achieved comparable efficacy in improving glycaemic control, reducing glycaemic variability, enhancing insulin sensitivity and ameliorating β-cell function. Therefore, repaglinide is an optional agent for initial therapy in Chinese patients with newly diagnosed T2DM.

NAP reduces murine microvascular endothelial cells proliferation induced by hyperglycemia

Hyperglycemia has been identified as a risk factor responsible for micro- and macrovascular complications in diabetes. NAP (Davunetide) is a peptide whose neuroprotective actions are widely demonstrated, although its biological role on endothelial dysfunctions induced by hyperglycemia remains uninvestigated. In the present study we hypothesized that NAP could play a protective role on hyperglycemia-induced endothelial cell proliferation. To this end we investigated the effects of NAP on an in vitro model of murine microvascular endothelial cells grown in high glucose for 7 days. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay and cyclin D1 protein expression analysis revealed that NAP treatment significantly reduces viability and proliferation of the cells. Hyperglycemia induced the activation of mitogen-activated protein kinase/extracellular signal-regulated protein kinase and/or phosphatidylinositol-3 kinase/Akt pathways in a time-dependent manner. NAP treatment reduced the phosphorylation levels of ERK and AKT in cells grown in high glucose. These evidences suggest that NAP might be effective in the regulation of endothelial dysfunction induced by hyperglycemia.

Increased risk of ischemic stroke after hyperosmolar hyperglycemic state: a population-based follow-up study

BACKGROUND

Although much attention has been focused on the association between chronic hyperglycemia and cerebrovascular diseases in type 2 diabetes mellitus (DM) patients, there is no data regarding the risk of ischemic stroke after a hyperosmolar hyperglycemic state (HHS) attack. The objective of this study was to investigate the risk of ischemic stroke in type 2 DM patients after an HHS attack.

METHODS

From 2004 to 2008, this retrospective observational study was conducted on a large cohort of Taiwanese using Taiwan's National Health Insurance Research Database (NHIRD). We identified 19,031 type 2 DM patients who were discharged with a diagnosis of HHS and 521,229 type 2 DM patients without an HHS diagnosis. Using the propensity score generated from logistic regression models, conditional on baseline covariates, we matched 19,031 type 2 DM patients with an HHS diagnosis with the same number from the comparison cohort. The one-year cumulative rate for ischemic stroke was estimated using the Kaplan-Meier method. After adjusting covariates, Cox proportional hazard regression was used to compute the adjusted one-year rate of ischemic stroke.

RESULTS

Of the patients sampled, 1,810 (9.5%) of the type 2 DM patients with HHS and 996 (5.2%) of the comparison cohort developed ischemic stroke during the one-year follow-up period. After adjusting for covariates, the adjusted HR for developing ischemic stroke during the one-year follow-up period was 1.8 (95% C.I., 1.67 to 1.95, P<0.001) for type 2 DM patients with HHS compared with those without HHS.

CONCLUSION

Although DM is a well-recognized risk factor for atherosclerosis, type 2 DM patients that have suffered a HHS attacks are at an increased risk of developing ischemic stroke compared with those without HHS.

Risks of diabetic nephropathy with variation in hemoglobin A1c and fasting plasma glucose

BACKGROUND

This study examined whether annual variation in glycosylated hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG), as represented by the coefficient of variation (CV), can predict diabetic nephropathy independently of mean FPG, mean HbA1c, and other risk factors in patients with type 2 diabetes.

METHODS

A computerized database of patients with type 2 diabetes aged ≥30 years and free of diabetic nephropathy (n = 3220) who were enrolled in the Diabetes Care Management Program of China Medical University Hospital before 2007 was used in a time-dependent Cox proportional hazards regression model.

RESULTS

The incidence rates of diabetic nephropathy were 16.11, 22.95, and 28.86 per 1000 person-years in the first, second, and third tertiles of baseline HbA1c-CV, respectively; the corresponding incidence rates for FPG-CV were 9.46, 21.23, and 37.51 per 1000 person-years, respectively. After multivariate adjustment, the corresponding hazard ratios for the second and third tertiles versus the first tertile of annual HbA1c-CV were 1.18 (95% confidence interval [CI], 0.88-1.58) and 1.58 (95% CI, 1.19-2.11), respectively, and 1.55 (95% CI, 0.99-2.41) and 4.75 (95% CI, 3.22-7.01) for FPG-CV, respectively. The risks of diabetic nephropathy for HbA1c-CV and FPG-CV stratified according to age, gender, renal function, and hypertension status were provided.

CONCLUSIONS

Annual FPG and HbA1c variations have a strong association with diabetic nephropathy in patients with type 2 diabetes. Whether intervention for reducing glucose variation should be administered needs to be examined in a future study.

Glycemic variability: Clinical implications

Glycemic control and its benefits in preventing microvascular diabetic complications are convincingly proved by various prospective trials. Diabetes control and complications trial (DCCT) had reported variable glycated hemoglobin (HbA1C) as a cause of increased microvascular complications in conventional glycemic control group versus intensive one. However, in spite of several indirect evidences, its link with cardiovascular events or macrovascular complications is still not proved. Glycemic variability (GV) is one more tool to explain relation between hyperglycemia and increased cardiovascular risk in diabetic patients. In fact GV along with fasting blood sugar, postprandial blood sugar, HbA1C, and quality of life has been proposed to form glycemic pentad, which needs to be considered in diabetes management. Postprandial spikes in blood glucose as well as hypoglycemic events, both are blamed for increased cardiovascular events in Type 2 diabetics. GV includes both these events and hence minimizing GV can prevent future cardiovascular events. Modern diabetes management modalities including improved sulfonylureas, glucagon like peptide-1 (GLP-1)-based therapy, newer basal insulins, and modern insulin pumps address the issue of GV effectively. This article highlights mechanism, clinical implications, and measures to control GV in clinical practice.

A1c variability can predict coronary artery disease in patients with type 2 diabetes with mean a1c levels greater than 7

BACKGROUND

Recent studies suggested that the association of acute glucose variability and diabetic complications was not consistent, and that A1c variability representing long term glucose fluctuation may be related to coronary atherosclerosis in patients with type 1 diabetes. In this study, we attempt to determine whether or not A1c variability can predict coronary artery disease (CAD) in patients with type 2 diabetes.

METHODS

We reviewed data of patients with type 2 diabetes who had undergone coronary angiography (CAG) and had been followed up with for 5 years. The intrapersonal standard deviation (SD) of serially-measured A1c levels adjusted by the different number of assessments among patients (adj-A1c-SD) was considered to be a measure of the variability of A1c.

RESULTS

Among the 269 patients, 121 of them had type 2 diabetes with CAD. In patients with A1c ≥7%, the mean A1c levels and A1c levels at the time of CAG among the three groups were significantly different. The ratio of patients with CAD was the highest in the high adj-A1c-SD group and the lowest in the low adj-A1c-SD group (P=0.017). In multiple regression analysis, adj-A1c-SD was an independent predictor for CAD in subjects with A1c ≥7% (odds ratio, 2.140; P=0.036).

CONCLUSION

Patients with higher A1c variability for several years showed higher mean A1c levels. A1c variability can be an independent predictor for CAD as seen in angiographs of patients with type 2 diabetes with mean A1c levels over 7%.

HbA1c variability is associated with an increased risk of retinopathy requiring laser treatment in type 1 diabetes

AIMS/HYPOTHESIS

This study aimed to investigate whether variation in long-term glycaemia in type 1 diabetes as measured by HbA1c variability is associated with the cumulative incidence and risk of retinopathy requiring laser treatment.

METHODS

The effect of HbA1c variability was assessed in 2,019 Finnish Diabetic Nephropathy (FinnDiane) study patients. The patients were studied in two partially overlapping subcohorts with either verified first laser treatment (n = 1,459) or retinopathy severity graded from ophthalmic records with the Early Treatment of Diabetic Retinopathy Study (ETDRS) scale (n = 1,346). The ratio of intrapersonal SD and mean of serially measured HbA1c was considered an estimate of HbA1c variability.

RESULTS

A subcohort of 1,459 patients did not have laser treatment prior to the first FinnDiane visit and 174 of these patients were treated during a mean follow-up period of 5.2 ± 2.2 years. The 5 year cumulative incidence of laser treatment was 19% (95% CI 15, 24) in the highest quartile of HbA1c variability and 10% (95% CI 7, 12) in the lowest quartile (p < 0.001, Gray's test) with a corresponding HR of 1.6 (95% CI 1.1, 2.5; p = 0.02) adjusted for renal status, diabetes duration, mean HbA1c, blood pressure, sex and number of HbA1c measurements. In a subcohort of 1,346 patients, 434 patients had proliferative diabetic retinopathy (PDR). Patients in the highest quartile of HbA1c variability had an increased risk of PDR compared with the lowest quartile (HR 1.7 [95% CI 1.3, 2.2]; p < 0.001]).

CONCLUSIONS/INTERPRETATION

HbA1c variability was associated with an increased cumulative incidence and risk of retinopathy requiring laser treatment in type 1 diabetes.

Glycemic variability in type 2 diabetes mellitus: oxidative stress and macrovascular complications

Diabetes mellitus is a world-wide health issue with potential for significant negative health outcomes, including microvascular and macrovascular complications. The relationship of hemoglobin HbA1c and other glycosylation end products (AGEs) to these complications, particularly microvascular disease, is well understood. More recent evidence suggests that glycemic variability may be associated with diabetes macrovascular complications. As HbA1c is better representative of average glucose levels and does not account as well for glycemic variability, hence new methods to assess and treat this variability is needed to reduce incidence of complications. In this chapter, the relationship of glycemic control to diabetes complications will be explored with focus on the mechanisms of tissue damage from this variability along with the oxidative stress. Additionally, treatment strategies to optimize HbA1c and glycemic variability with the goal of reducing risk of complications in persons with diabetes are reviewed.

Protection of exenatide for retinal ganglion cells with different glucose concentrations

Exendin-4 is a peptide resembling glucagon-like peptide-1 (GLP-1), which has protective effects on nerve cells. However, the effects of Exendin-4 on retinal ganglion cells (RGC) are still under clear. The purpose of the present study is to demonstrate that exenatide prevents high- or low-glucose-induced retinal ganglion cell impairment. We observed the expression of GLP-1R in RGC-5 cells by immunofluorescence and Western blot. To investigate the effect of exenatide on RGC-5 cells incubated different glucose concentrations, CCK-8 measured the survival rates and electron microscopy detected cellular injury. The expression levels of Bcl-2 and Bax were analyzed by immunocytochemistry and Western blot. Exenatide protects RGC-5 from high- or low-glucose-induced cellular injury and the optimum concentration was 0.5μg/ml. Exenatide can inhibit high- or low-glucose-induced mitochondrial changes. Exenatide protects RGC-5 from high- or low-glucose-induced Bax increased and Bcl-2 decreased. Furthermore, the protective effect of exenatide could be inhibited by Exendin (9-39). These findings indicate that exenatide shows a neuroprotective effect for different glucose concentrations-induced RGC-5 cells injury. Exenatide could protect RGC-5 cells from degeneration or death, which may protect retinal function and have a potential value for patients with diabetic retinopathy.