Dapagliflozin improves skeletal muscle insulin sensitivity through SIRT1 activation induced by nutrient deprivation state.

Lipid peroxidation and mitochondrial damage impair insulin sensitivity in skeletal muscle. Sirtuin-1 (SIRT1) protects mitochondria and activates under energy restriction. Dapagliflozin (Dapa) is an antihyperglycaemic agent that belongs to the sodium-glucose cotransporter-2 (SGLT2) inhibitors. Evidence shows that Dapa can induce nutrient deprivation effects, providing additional metabolic benefits. This study investigates whether Dapa can trigger nutrient deprivation to activate SIRT1 and enhance insulin sensitivity in skeletal muscle. We treated diet-induced obese (DIO) mice with Dapa and measured metabolic parameters, lipid accumulation, oxidative stress, mitochondrial function, and glucose utilization in skeletal muscle. ß-hydroxybutyric acid (ß-HB) was intervened in C2C12 myotubes. The role of SIRT1 was verified by RNA interference. We found that Dapa treatment induced nutrient deprivation state and reduced lipid deposition and oxidative stress, improved mitochondrial function and glucose tolerance in skeletal muscle. The same positive effects were observed after ß-HB intervening for C2C12 myotubes, and the promoting effects on glucose utilization were diminished by SIRT1 RNA interference. Thus, Dapa promotes a nutrient deprivation state and enhances skeletal muscle insulin sensitivity via SIRT1 activation. In this study, we identified a novel hypoglycemic mechanism of Dapa and the potential mechanistic targets.

Berberine Slows the Progression of Prediabetes to Diabetes in Zucker Diabetic Fatty Rats by Enhancing Intestinal Secretion of Glucagon-Like Peptide-2 and Improving the Gut Microbiota.

Background: Berberine is a plant alkaloid that has multiple beneficial effects against intestine inflammation. In our previous study, we have found that berberine also possesses an antidiabetic effect. However, whether berberine is useful in the prevention of type 2 diabetes mellitus (T2DM) through its effect on intestine endocrine function and gut microbiota is unclear. Aim: To investigate the effects of berberine in the prevention of T2DM, as well as its effects on intestine GLP-2 secretion and gut microbiota in ZDF rats. Methods: Twenty Zucker Diabetic Fatty (ZDF) rats were fed a high-energy diet until they exhibited impaired glucose tolerance (IGT). The rats were then divided into two groups to receive berberine (100 mg/kg/d; berberine group) or vehicle (IGT group) by gavage for 3 weeks. Five Zucker Lean (ZL) rats were used as controls. Fasting blood glucose (FBG) was measured, an oral glucose tolerance test was performed, and the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was calculated. Intestinal expression of TLR-4, NF-κB, TNF-α, mucin, zona occludens-1 (ZO-1) and occludin were assessed (immunohistochemistry). Plasma levels and glutamine-induced intestinal secretion of glucagon-like peptide-1 (GLP-1) and GLP-2 were measured (enzyme-linked immunosorbent assay). The plasma lipopolysaccharide (LPS) level was measured. Fecal DNA extraction, pyrosequencing, and bioinformatics analysis were performed. Results: After 3 weeks of intervention, diabetes developed in all rats in the IGT group, but only 30% of rats in the berberine group. Treatment with berberine was associated with reductions in food intake, FBG level, insulin resistance, and plasma LPS level, as well as increases in fasting plasma GLP-2 level and glutamine-induced intestinal GLP-2 secretion. Berberine could increase the goblet cell number and villi length, and also reverse the suppressed expressions of mucin, occludin, ZO-1 and the upregulated expressions of TLR-4, NF-κB and TNF-α induced in IGT rats (P<0.05). Berberine also improved the structure of the gut microbiota and restored species diversity. Conclusion: Berberine may slow the progression of prediabetes to T2DM in ZDF rats by improving GLP-2 secretion, intestinal permeability, and the structure of the gut microbiota.

Establishment and Validation of a Risk Prediction Model for Early Diabetic Kidney Disease Based on a Systematic Review and Meta-Analysis of 20 Cohorts.

BACKGROUND: Identifying patients at high risk of diabetic kidney disease (DKD) helps improve clinical outcome. PURPOSE: To establish a model for predicting DKD. DATA SOURCES: The derivation cohort was from a meta-analysis. The validation cohort was from a Chinese cohort. STUDY SELECTION: Cohort studies that reported risk factors of DKD with their corresponding risk ratios (RRs) in patients with type 2 diabetes were selected. All patients had estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 and urinary albumin-to-creatinine ratio (UACR) <30 mg/g at baseline. DATA EXTRACTION: Risk factors and their corresponding RRs were extracted. Only risk factors with statistical significance were included in our DKD risk prediction model. DATA SYNTHESIS: Twenty cohorts including 41,271 patients with type 2 diabetes were included in our meta-analysis. Age, BMI, smoking, diabetic retinopathy, hemoglobin A1c, systolic blood pressure, HDL cholesterol, triglycerides, UACR, and eGFR were statistically significant. All these risk factors were included in the model except eGFR because of the significant heterogeneity among studies. All risk factors were scored according to their weightings, and the highest score was 37.0. The model was validated in an external cohort with a median follow-up of 2.9 years. A cutoff value of 16 was selected with a sensitivity of 0.847 and a specificity of 0.677. LIMITATIONS: There was huge heterogeneity among studies involving eGFR. More evidence is needed to power it as a risk factor of DKD. CONCLUSIONS: The DKD risk prediction model consisting of nine risk factors established in this study is a simple tool for detecting patients at high risk of DKD.

Hyperinsulinemia Can Cause Kidney Disease in the IGT Stage of OLETF Rats via the INS/IRS-1/PI3-K/Akt Signaling Pathway.

AIMS: We investigated the changes of renal structure and its function in normal glucose tolerance (NGT), impaired glucose tolerance (IGT), diabetes mellitus (DM), and diabetic kidney disease (DKD) stages in OLETF rats and explored the role of the INS/IRS-1/PI3-K/Akt signaling pathway. METHODS: OLETF rats were assigned into four groups on the basis of OGTT results and 24 h urinary microalbumin: NGT, IGT, DM, and DKD groups. The changes of renal structure and function and the corresponding pathological changes were observed. The absorption of albumin and the expression of megalin, cubilin, IRS-1, PI3-K, and Akt in NRK-52E cells were measured after being stimulated by different concentrations of insulin. RESULTS: In the IGT group, the index which reflects the function of renal tubule-like N-acetyl-ß-glucosaminidase, neutrophil gelatinase-associated lipocalin, retinol-binding protein, and cystatin C was higher than those in the control group and the NGT group (P < 0.05). Significant renal structure damages, especially in renal tubules, were observed in the IGT group. In the presence of insulin at a high concentration, the IRS-1/PI3-K/Akt signaling pathway in renal tubular epithelial cells was inhibited, and the expression of megalin and cubilin was significantly downregulated which was accompanied by a minimum uptake of albumin. CONCLUSIONS: In contrast to DKD, the renal structural damage and functional changes in the IGT stage, in which we propose the term "IGT kidney disease," mainly manifest as renal tubular injury. Insulin resistance and compensatory hyperinsulinemia may be involved in its pathogenesis.

Relationship between inflammatory markers and mild cognitive impairment in Chinese patients with type 2 diabetes: a case-control study.

BACKGROUND: Several studies have indicated that inflammatory markers were associated with the risk of mild cognitive impairment (MCI) in type 2 diabetes (T2D). Serum folate was related to MCI as well as inflammation. However, no studies have investigated the association between inflammatory markers and MCI taking account of serum folate level in T2D patients. This study aimed to conduct a case-control study to evaluate the association between inflammatory markers and MCI taking account of serum folate level in Chinese patients with T2D. METHODS: This study consisted of 126 T2D patients (63 cases with MCI and 63 controls without MCI). Clinical parameters, serum folate, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) were measured. Spearman correlation analysis and logistic regression analysis were used to analyze the association between the inflammatory markers and the risk of MCI in T2D patients. RESULTS: There were higher serum hs-CRP, IL-6 and TNF-α in T2D cases with MCI compared with the controls. Serum folate was negatively correlated with hs-CRP, TNF-α, and IL-6 (P < 0.05). In multivariate analysis, there were significant associations between serum IL-6 or hs-CRP and MCI after adjusting for the confounding variables, however, the association between hs-CRP and MCI disappeared after further adjusting for serum folate. Further subgroup analysis revealed that the significant association between hs-CRP and MCI only existed in the low folate subgroup (< 7.0 µg/L; OR = 3.34, 95% CI: 1.05-10.64), not in the high folate subgroup (≥7.0 µg/L; OR = 2.16, 95% CI: 0.68-6.88) after adjusting for the confounding variables. CONCLUSIONS: Serum IL-6 and hs-CRP were associated with the risk of MCI in Chinese patients with T2D. Serum folate might modify the association between serum hs-CRP and MCI in T2D patients.

Folic Acid Reduces Tau Phosphorylation by Regulating PP2A Methylation in Streptozotocin-Induced Diabetic Mice.

High incidence rate of Alzheimer's disease (AD) is observed in patients with type 2 diabetes. Aggregated ß-amyloid (Aß) and hyperphosphorylated tau are the hallmarks of AD. Hyperphosphorylated tau has been detected in diabetic animals as well as in diabetic patients. Folates mediate the transfer of one carbon unit, required in various biochemical reactions. The effect of folate on tau phosphorylation in diabetic models still remains unknown. In this study, we investigated the effect and mechanism of folic acid on hyperphosphorylation of tau in streptozotocin (STZ)-induced diabetic mice. Diabetic mice induced by STZ, at the age of 10 weeks, were administered with three levels of folic acid: folic acid-deficient diet, diet with normal folic acid content, and 120 µg/kg folic acid diet for 8 weeks. Levels of serum folate and blood glucose were monitored. Tau phosphorylation, protein phosphatase 2A (PP2A) methylation, and Glycogen synthase kinase 3ß (GSK-3ß) phosphorylation were detected using Western blot. The S-adenosyl methionine:S-adenosyl homocysteine ratio (SAM:SAH) in brain tissues was also determined. DNA methyltransferase (DNMT) mRNA expression levels were detected using real-time PCR. Folic acid reduced tau hyperphosphorylation at Ser396 in the brain of diabetes mellitus (DM) mice. In addition, PP2A methylation and DNMT1 mRNA expression were significantly increased in DM mice post folic acid treatment. GSK-3ß phosphorylation was not regulated by folic acid administration. Folic acid can reduce tau phosphorylation by regulating PP2A methylation in diabetic mice. These results support that folic acid can serve as a multitarget neuronal therapeutic agent for treating diabetes-associated cognitive dysfunction.

Factors Associated with Frontotemporal Dementia in China: A Cross-Sectional Study.

BACKGROUND AND AIMS: There is a growing focus on frontotemporal dementia (FTD). However, compared with other major dementias, very little is known about the factors associated with FTD. The present study evaluated candidate factors associated with FTD in the Chinese population. METHODS: One hundred eight elderly patients (36 diagnosed with FTD and 72 controls) of the Neurology Central Hospital of Tianjin (China), were diagnosed by neurologists, and recruited for the study between November 2011 and November 2014. Clinical evaluation, laboratory tests, brain images (computed tomography scans and magnetic resonance images), neuropsychological, and neuropsychiatric assessments were performed. The association between FTD and the variables was assessed using multiple binary logistic regression analyses adjusted for age and gender. RESULTS: With controls as the reference category, education was associated with the diagnosis of FTD (adjusted odds ratio [OR], 1.60; 95% confidence interval [CI]: 1.17-2.19). Serum vitamin B12 levels were associated with the diagnosis of FTD (adjusted OR, 0.99; 95% CI: 0.98-0.99). Serum low-density lipoprotein (LDL) levels were associated with the diagnosis of FTD (adjusted OR, 8.54; 95% CI: 2.86-25.49). CONCLUSIONS: Education and serum LDL levels were positively associated with the diagnosis of FTD. Serum vitamin B12 levels were negatively associated with the diagnosis of FTD.

Atorvastatin inhibits insulin synthesis by inhibiting the Ras/Raf/ERK/CREB pathway in INS-1 cells.

BACKROUND: Type 2 diabetes has become a global epidemic disease. Atorvastatin has become a cornerstone in the prevention and treatment of atherosclerosis. However, increasing evidence showed that statins can dose-dependently increase the risk of diabetes mellitus. The mechanism is not clear. OBJECTIVE: The Ras complex pathway (Ras/Raf/extracellular signal-regulated kinase [ERK]/cAMP response element-binding protein [CREB]) is the major pathway that regulates the gene transcription. Except for the inhibition of cholesterol synthesis by inhibiting the 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-COA) reductase, statins can also downregulate the phosphorylation of a series of downstream substrates including the key proteins of the Ras complex pathway, therefore may inhibit the insulin syntheses in pancreatic beta cells. In our study, we investigated the inhibitory effect and the underlying mechanism of atorvastatin on insulin synthesis in rat islets. METHODS: Islets were isolated from Wistar rats and cultured in Roswell Park Memorial Institute (RPMI)-1640 medium. The insulin content in the medium was measured by radioimmunoassay before and after the treatment of 50 µM atorvastatin. Effect of atorvastatin on the expression of insulin message Ribonucleic acid (mRNA) in pancreatic islet beta cells was also detected using quantitative real-time polymerase chain reaction. Western blotting was used to explore the possible role of the Ras complex pathway (Ras/Raf/ERK/CREB) in atorvastatin-inhibited insulin synthesis. The effects of atorvastatin on the binding of nuclear transcription factor p-CREB with CRE in INS-1 cells were examined via chromatin immunoprecipitation assay. RESULTS: Compared with the control group, the insulin level decreased by 27.1% at 24 hours after atorvastatin treatment. Atorvastatin inhibited insulin synthesis by decreasing insulin mRNA expression of pancreatic islet beta cells. The activities of Ras, Raf-1, and p-CREB in the Ras complex pathway were inhibited by 50 µM atorvastatin in INS-1 cells in vitro. Moreover, 50 µM atorvastatin reduced the binding of p-CREB with deoxyribonucleic acid (DNA) in INS-1 cells in vitro. CONCLUSION: Atorvastatin inhibits insulin synthesis in beta cells by inhibiting the activation of the Ras complex pathway.

Folic Acid Supplementation Mitigates Alzheimer's Disease by Reducing Inflammation: A Randomized Controlled Trial.

Background/Aims. Low serum folate levels can alter inflammatory reactions. Both phenomena have been linked to Alzheimer's disease (AD), but the effect of folic acid on AD itself is unclear. We quantified folate supplementation's effect on inflammation and cognitive function in patients with AD over the course of 6 months. Methods. Patients newly diagnosed with AD (age > 60 years; n = 121; mild to severe; international criteria) and being treated with donepezil were randomly assigned into two groups with (intervention group) or without (control group) supplemental treatment with folic acid (1.25 mg/d) for 6 months. The Mini-Mental State Examination (MMSE) was administered to all patients at baseline and follow-up, and blood samples were taken before and after treatment. We quantified serum folate, amyloid beta (Aß), interleukin-6 (IL-6), tumor necrosis factor α (TNFα), plasma homocysteine (Hcy), S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), and the mRNA levels of presenilin (PS), IL-6, and TNFα in leukocytes. Data were analyzed using a repeated-measures mixed model. Results. The mean MMSE was slightly increased in the intervention group compared to that in the control group (P < 0.05). Posttreatment, plasma SAM and SAM/SAH levels were significantly higher (P < 0.05), while Aß 40, PS1-mRNA, and TNFα-mRNA levels were lower in the intervention group than in the control group (P < 0.05). The Aß 42/Aß 40 ratio was also higher in the intervention group (P < 0.05). Conclusions. Folic acid is beneficial in patients with AD. Inflammation may play an important role in the interaction between folic acid and AD. This trial is registered with clinical trial registration number ChiCTR-TRC-13003246.

Effects of metformin and sitagliptin on glycolipid metabolism in type 2 diabetic rats on different diets.

INTRODUCTION: The aim of the study was to investigate the effects of metformin and sitagliptin on glycolipid metabolism in type 2 diabetes after different diets. MATERIAL AND METHODS: Seventy Male Sprague Dawley rats were fed with a high fat diet followed by streptozotocin treatment to induce type 2 diabetes. Then all rats were randomly divided into a control group, a metformin group (200 mg/kg), and a sitagliptin group (10 mg/kg). Each group was further divided into 4 groups receiving one load of high carbohydrate diet (45% glucose, 4.5 ml/kg), high fat diet (20% lipid emulsion, 4.5 ml/kg), high protein diet (20% whey protein, 10 ml/kg) or mixed meal, respectively. The caloric densities were all 33 kJ/kg. Postprandial blood glucose (P2BG), triglyceride (TG), glucagon-like peptide-1 (GLP-1), glucagon and insulin levels were measured. RESULTS: In the high carbohydrate group, sitagliptin was more efficient in lowering P2BG compared with metformin (p < 0.05). In the high-fat group, metformin was more powerful in lowering TG (p < 0.05) and P2BG (p < 0.05) levels because of its improvement of insulin sensitivity. In the high protein diet group, metformin did not reduce the P2BG level (p > 0.05), although it did reduce the TG level (p < 0.05). In the mixed diet group, metformin was more efficient in lowering P2BG (p < 0.05) but had a similar effect on TG (p > 0.05) compared with sitagliptin. CONCLUSIONS: In the type 2 diabetic model, metformin and sitagliptin have different effects on glycolipid metabolism after different diets. If it is proved in type 2 diabetic patients, then different medicines may be recommended according to different diets in order to improve glycolipid metabolism.

Glucagon secretion is increased in patients with Type 2 diabetic nephropathy.

AIMS: Currently little is known about the relationship between renal function, albuminuria and glucagon; we analyzed the secretion of glucagon (GLA) and C-peptide in Type 2 diabetic patients with different degrees of nephropathy. METHODS: 357 patients with Type 2 diabetes including 119 cases without nephropathy and 238 cases with nephropathy were divided into four groups according to the stages of diabetic nephropathy. Patients with diabetic nephropathy were further classified according to the level of estimated glomerular filtration rate (eGFR). OGTT and insulin, C-peptide, glucagon releasing tests were performed in all patients. Characteristics of glucagon and C-peptide secretion in different groups were compared. Glucagon/glucose ratio (GLA/GLU) and glucagon/insulin ratio (GLA/INS) were used to represent the inhibition of glucose or insulin on glucagon secretion, respectively. RESULTS: With the progress of diabetic nephropathy, glucagon level increased significantly; the glucagon peak after glucose load delayed from 60 min to 120 min, whereas C-peptide level decreased significantly. Related factors analysis suggested that glucagon was independently correlated with eGFR. Further analysis showed that glucagon level was higher in group with eGFR<60 ml/min compared with that in group with eGFR≥60 ml/min. In addition, both GLA/INS and GLA/GLU were higher in group with eGFR<60 ml/min compared with those in group with eGFR≥60 ml/min. CONCLUSIONS: Patients with Type 2 diabetic nephropathy have worsened islet alpha and beta cell function. Therefore medications based on the regulation of glucagon secretion may improve glycemic control and also be beneficial for delaying the progress of diabetic nephropathy.

[Association between sleep disorder and osteoporosis in elderly female patients with type 2 diabetes mellitus].

OBJECTIVE: To explore the association between sleep disorder and osteoporosis in elderly female patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 536 elderly female T2DM patients from July 2011 to July 2014 were divided into two groups of patients without sleep disorder and those with sleep disorder based upon the Pittsburgh Sleep Quality Index. The bone mineral density of femoral neck, Wards triangle, greater trochanter and lumbar spines (L2-L4) were measured by dual-energy X-ray absorptiometry. Biochemical indicators were detected in two groups. Oral glucose tolerance and insulin releasing tests were performed. We compared the differences of bone mineral density and ß-cell function after fasting and glucose-load. The logistic regression analyses were performed between sleep disorder and osteoporosis and other indicators. RESULTS: The levels of high sensitivity C-reactive protein (hs-CRP), HbA1c, cortisol (COR), adrenocorticotropic hormone (ACTH), fasting insulin (FINS) and homeostasis model assessment-estimated insulin resistance (HOMA-IR) were significantly higher in patients with sleep disorder compared to those without sleep disorder [(3.5 ± 1.1) vs (2.6 ± 0.9) mg/L, (8.0 ± 1.9)% vs (7.3 ± 1.6)%, (512 ± 88) vs (436 ± 76) nmol/L, (6.4 ± 2.3) vs (5.1 ± 2.0) pmol/L, (13.4 ± 4.3) vs (12.4 ± 4.0) mU/L, 4.7 ± 0.8 vs 3.8 ± 0.8, all P < 0.05]. Insulin sensitivity index (ISI) was lower in patients with sleep disorder than that in patients without sleep disorder (-4.2 ± 0.5 vs -4.0 ± 0.4, P < 0.05). The bone mineral density of femoral neck, Wards triangle, greater trochanter and lumbar spines (L2-L4) were significantly lower and the prevalence rate of osteoporosis was significantly higher in patients with sleep disorder compared to those in patients without sleep disorder (all P < 0.05). Logistic regression analysis showed that sleep disorder was positively correlated with HOMA-IR, HbA1c, COR and ACTH (all P < 0.05) and negatively with ISI (P < 0.05). Logistic regression analysis showed that osteoporosis was positively correlated with postmenopausal duration, HbA1c, COR, ACTH and sleep disorder (all P < 0.05) and negatively with ISI (P < 0.05). CONCLUSION: Sleep disorder causes osteoporosis through various mechanisms in elderly female T2DM patients. Improving sleep disorder may help to reduce the prevalence of osteoporosis.

[Association between retinopathy and sleep disorder in patients with type 2 diabetes mellitus].

OBJECTIVE: To explore the association between retinopathy and sleep disorder in patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 440 patients with T2DM treated from July 2011 to July 2013 in Metabolic Disease Hospital of Tianjin Medical University were divided into 2 groups according to Pittsburgh Sleep Quality Index: non-sleep disorder group (258 cases) and sleep disorder group (182 cases). Biochemical parameters including hepatorenal function, blood lipids, glycosylated hemoglobin (HbA1c), fructosamine and hemorrheology were detected. Oral glucose tolerance test, insulin releasing test and glucagon releasing test were performed to detect the inteR-group differences of α-cell and ß-cell function after fasting and glucose-load management. The logistic regression analysis was performed to identify the factors relevant to retinopathy. RESULTS: The ratio of retinopathy was 42.9% in sleep disorder group, which was higher compared to those in non-sleep disorder group (32.6%), P=0.027. The levels of fasting plasma glucose, postprandial blood glucose, HbA1c, fructosamine, systolic blood pressure, diastolic blood pressure and the indicators of hemorrheology (plasma viscosity, erythrocyte aggregation index, erythrocyte rigidity index, fibrinogen) were significantly higher in patients with sleep disorder compared to those without sleep disorder, while the erythrocyte defomation index was significantly lower in sleep disorder group (all P<0.05). The levels of glucagon and glucagon/insulin ratio at each time point as well as area under curve of glucagon were significantly higher in sleep disorder group (all P<0.05). The levels of fasting insulin, homeostasis model assessment for insulin resistance index (HOMA-IR) and area under curve of insulin were significantly higher in patients with sleep disorder compared to those without sleep disorder, while insulin sensitivity index was lower in patients with sleep disorder (all P<0.05). Logistic regression analysis showed that retinopathy was positively related to HbA1c (OR: 1.744-3.249), fibrinogen (OR: 1.687-2.998), systolic blood pressure (OR: 1.152-2.013), HOMA-IR (OR: 1.006-1.389) and sleep disorder (OR: 1.144-2.426), and negatively related to insulin sensitivity index (OR: 0.107-0.784) (all P<0.05). CONCLUSION: Sleep disorders may be associated with retinopathy through multiple mechanisms in patients with T2DM.

[Association between sleep disorders and dawn phenomenon in patients with type 2 diabetes mellitus].

OBJECTIVE: To explore the association between sleep disorders and dawn phenomenon in patients with type 2 diabetes mellitus (T2DM). METHODS: From July 2011 to July 2014 at Metabolic Disease Hospital, Tianjin Medical University, 316 T2DM patients on continuous glucose monitoring were divided into two groups according to the Pittsburgh Sleep Quality Index, i.e. those without sleep disorders (n = 186) and those with sleep disorders (n = 130). Biochemical parameters including hepatorenal functions, blood lipids, glycosylated hemoglobin (HbA1c) and fructosamine were detected. Oral glucose tolerance test, insulin releasing test and glucagon releasing test were performed to detect the inter-group differences of glucose concentration and α-cell and ß-cell functions after fasting and glucose loading. And the correlation and regression analyses were performed between sleep disorders and other parameters. RESULTS: The level of HbA1c, fructosamine, increment of fasting glucose and nocturnal nadir glucose, glucose increment before and after breakfast, 24 h mean glucose, fasting insulin, homeostasis model assessment of insulin resistance index (HOMA-IR) and area under curve of insulin were significantly higher in patients with sleep disorders than those without sleep disorders (8.2% ± 2.0% vs 7.4% ± 1.7%, (0.33 ± 0.10) vs (0.29 ± 0.07) mmol/L, (1.511 ± 0.294) vs (0.889 ± 0.233) mmol/L, (2.144 ± 0.400) vs (1.522 ± 0.378) mmol/L, (9.917 ± 1.800) vs (8.694 ± 1.622) mmol/L, (13.49 ± 4.68) vs (12.16 ± 4.56) mU/L, 4.98 ± 0.90 vs 3.82 ± 0.82, (8.47 ± 0.59) vs (8.25 ± 0.54), all P < 0.05). Insulin sensitivity index was lower in patients with sleep disorders than that in those without sleep disorders (-4.28 ± 0.62 vs -4.03 ± 0.52, P < 0.05). The level of glucagon at each timepoint and area-under-curve of glucagon were significantly higher in patients with sleep disorders than those without sleep disorders. The levels of 0, 30, 180 min glucagon/insulin ratio and glucagon/glucose ratio were significantly higher in patients with sleep disorders (all P < 0.05). Sleep disorder was positively correlated with HOMA-IR, glucagon/insulin ratio, increment of fasting glucose and nocturnal nadir glucose and dawn phenomenon (all P < 0.05). Yet there was a negative correlation with insulin sensitivity index (P < 0.05). CONCLUSIONS: Sleep disorders are associated with dawn phenomenon. And improving sleep disorder helps to improve the dawn phenomenon and optimize overall glycemic control.

Relationship between circadian blood pressure variability and function of islet α and ß cell in type 2 diabetes with dyssomnia.

AIMS: To investigate the relationship between circadian blood pressure (BP) variability and function of islet α and ß cell in type 2 diabetes (T2D) with dyssomnia. METHODS: Patients with T2D were divided into dyssomnia group and non-dyssomnia group by PSQI. OGTT, insulin and glucagon-releasing test were tested, and ambulatory BP was monitored for 24 hours to compare two groups with α and ß cell, circadian BP variability and fasting and post-meal BP variability. The correlation and regression analysis were made between PSQI and other indicators. RESULTS: In dyssomnia group, ① Glucagon, glucagon/insulin ratio and AUCG were significantly higher (P < 0.05). ② Fasting insulin (13.32 ± 4.54 mIU/L), AUCI (8.51 ± 0.54) and HOMA-IR (4.62 ± 1.11) were high (P < 0.05). But ISI (-4.27 ± 0.77) was low (P < 0.05). ③ Mean 24-hour and nighttime SBP and DBP, as well as their standard deviations and coefficients of variation, were all higher in the dyssomnia group (P < 0.05). Multiple stepwise regression analysis showed that PSQI score was positively related to AUCG, HOMA-IR, nighttime SBP, and negatively related to ISI and nocturnal BP fall (P < 0.05). CONCLUSION: Dyssomnia may cause abnormal circadian BP variability through various mechanisms. Improving dyssomnia can help to better function the islet α and ß cell and restore normal circadian BP variability.

Renal tubular damage may contribute more to acute hyperglycemia induced kidney injury in non-diabetic conscious rats.

AIMS: Growing evidences suggest that acute hyperglycemia is strongly related to kidney injury. Our study aimed to investigate the effects of acute hyperglycemia on kidney glomerular and tubular impairment in non-diabetic conscious rats. METHODS: Non-diabetic conscious rats were randomly subjected to 6h of saline (control group) or high glucose (acute hyperglycemia group) infusion. Blood glucose was maintained at 16.0-18.0 mmol/L in acute hyperglycemia group. Renal structure and function alterations, systemic/renal inflammation and oxidative stress markers were assessed, and apoptosis markers of renal inherent cells were evaluated. RESULTS: Acute hyperglycemia caused significant injury to structure of glomerular filtration barrier, tubular epithelial cells and peritubular vascular endothelial cells. It increased urinary microalbumin (68.01 ± 27.09 µg/24h vs 33.81 ± 13.81 µg/24h , P=0.014), ß2-microglobulin, Cystatin C, urinary and serous neutrophil gelatinase-associated lipocalin levels (P < 0.05). Acute hyperglycemia decreased megalin and cubilin expression, activated systemic and renal oxidative stress as well as inflammation and promoted renal inherent cell apoptosis. CONCLUSIONS: Acute hyperglycemia causes significant injury to kidney function and structure. Compared with damages of glomerular filtration barrier, renal tubular injury may contribute more to acute hyperglycemia induced proteinuria. Activation of inflammation especially renal inflammation, oxidative stress and enhanced apoptosis may be the underlying mechanisms.

Associations between Alzheimer's disease and blood homocysteine, vitamin B12, and folate: a case-control study.

BACKGROUND: There is a growing focus on nutritional therapy for Alzheimer's disease (AD), and controversy exists regarding the association between AD and homocysteine (Hcy), vitamin B12, and folate levels. OBJECTIVE: The present study evaluated the association between AD and the combined levels of Hcy, vitamin B12, and folate. METHODS: This case-control study consisted of 115 patients with AD and 115 matched controls. Serum folate and vitamin B12 were measured using an automated immunoassay analyzer. Plasma Hcy was measured using high-performance liquid chromatography. The association between AD and Hcy, vitamin B12, and folate was analyzed using binary logistic regression, adjusted for age and sex. RESULTS: With the combination of normal blood Hcy, vitamin B12, and folate levels as the reference category, low vitamin B12 in subjects with normal Hcy and folate was associated with AD (adjusted odds ratio [OR], 4.6; 95% confidence interval [CI]: 1.6-13.2). The combination of low vitamin B12 and folate in subjects with normal Hcy was associated with AD (adjusted OR, 4.3; 95% CI: 1.3-14.6). The combination of high Hcy and low folate levels in patients with normal vitamin B12 was associated with AD (adjusted OR, 17.0; 95% CI: 5.4- 53.4). The combination of high Hcy, low vitamin B12, and any folate level was associated with AD (adjusted OR, 30.5; 95% CI: 9.7-95.9). CONCLUSION: Vitamin B12 was directly associated with AD. The combination of high Hcy, low vitamin B12, and any folate level represented the poorest association with AD.

Relationship between blood levels of methyl donor and folate and mild cognitive impairment in Chinese patients with type 2 diabetes: a case-control study.

Type 2 diabetes is a risk factor for Alzheimer's disease and mild cognitive impairment. Folate insufficiency fosters a decline in the sole methyl donor, S-adenosylmethionine, and decreases methylation potential, which is associated with Alzheimer's disease in non-diabetic patients. However, little is known in diabetic patients. We analyzed plasma levels of S-adenosylmethionine, S-adenosylhomocysteine and serum level of folate in 100 elderly type 2 diabetic patients with and without mild cognitive impairment. S-adenosylmethionine/S-adenosylhomocysteine ratio was used to reflect the methylation potential. Patients with mild cognitive impairment had significantly lower levels of S-adenosylmethionine, folate and S-adenosylmethionine/S-adenosylhomocysteineratios. Furthermore, logistic regression analysis indicated the plasma S-adenosylmethionine, S-adenosylmethionine/S-adenosylhomocysteine ratio and serum folate (OR, 0.96, 0.698, 0.72, respectively; p<0.05) were negatively associated with risk of mild cognitive impairment, even after adjusting for related covariates. In addition, folate level was positively correlated with S-adenosylmethionine and the S-adenosylmethionine/S-adenosylhomocysteine ratio (r = 0.38, 0.46, respectively; p<0.05) among patients within the middle tertile of folate levels (6.3-9.1 µg/L). These findings indicate mild cognitive impairment is associated with lower levels of S-adenosylmethionine, folate and weakened methylation potential; plasma S-adenosylmethionine and methylation potential may be predicted by serum folate within a suitable range of folate concentrations in diabetic patients.

Effects of 24-week treatment with acarbose on glucagon-like peptide 1 in newly diagnosed type 2 diabetic patients: a preliminary report.

BACKGROUND: Treatment with the alpha-glucosidase inhibitor (AGI) acarbose is associated with a significant reduction the risk of cardiovascular events. However, the underlying mechanisms of this effect are unclear. AGIs were recently suggested to participate in stimulating glucagon-like peptide 1 (GLP-1) secretion. We therefore examined the effects of a 24-week treatment of acarbose on endogenous GLP-1, nitric oxide (NO) levels, nitric oxide synthase (NOS) activity, and carotid intima-media thickness (CIMT) in newly diagnosed patients with type 2 diabetes (T2D). METHODS: Blood was drawn from 24 subjects (14 male, 10 female, age: 50.7 ± 7.36 years, BMI: 26.64 ± 3.38 kg/m2, GHbA1c: 7.00 ± 0.74%) with drug-naïve T2D at 0 and 120 min following a standard mixed meal for the measurements of active GLP-1, NO and NOS. The CIMT was measured prior to and following 24 weeks of acarbose monotherapy (mean dose: 268 mg daily). RESULTS: Following 24 weeks of acarbose treatment, both fasting and postprandial plasma GLP-1 levels were increased. In patients with increased postprandial GLP-1 levels, serum NO levels and NOS activities were also significantly increased and were positively related to GLP-1 levels. Although the CIMT was not significantly altered following treatment with acarbose, a decreased CIMT was negatively correlated with increased GLP-1 levels. CONCLUSIONS: Twenty-four weeks of acarbose monotherapy in newly diagnosed patients with T2D is associated with significantly increased levels of both fasting and postprandial GLP-1 as well as significantly increased NO levels and NOS activity for those patients in whom postprandial GLP-1 levels were increased. Therefore, the benefits of acarbose on cardiovascular risk may be related to its stimulation of GLP-1 secretion.