The cutoffs and performance of glycated hemoglobin for diagnosing diabetes and prediabetes in a young and middle-aged population and in an elderly population.

The aims were to compare the appropriate cutoffs of glycated hemoglobin (HbA1c) in a population of varying ages and to evaluate the performance of HbA1c for diagnosing diabetes and prediabetes. A total of 1064 participants in the young and middle-aged group and 1671 in the elderly group were included and underwent HbA1c testing and an oral glucose tolerance test (OGTT). Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated to evaluate the optimal HbA1c cutoffs. Kappa coefficients were used to test for agreement between HbA1c categorization and OGTT-based diagnoses. The optimal HbA1c cutoffs for diagnosing diabetes were 5.7% (39 mmol/mol) in the young and middle-aged group with a sensitivity of 66.7%, specificity of 86.7%, and AUC of 0.821 (95% CI: 0.686, 0.955) and 5.9% (41 mmol/mol) in the elderly group with a sensitivity of 80.4%, specificity of 73.3%, and AUC of 0.831 (0.801, 0.861). The optimal cutoffs for diagnosing prediabetes were 5.6% (38 mmol/mol) and 5.7% (39 mmol/mol) in the young and middle-aged group and in the elderly group, respectively. Agreement between the OGTT-based diagnosis of diabetes or prediabetes and the optimal HbA1c cutoff was low (all kappa coefficients <0.4). The combination of HbA1c and fasting plasma glucose increased diagnostic sensitivities or specificities. In conclusion, age-specific HbA1c cutoffs for diagnosing diabetes or prediabetes were appropriate. Furthermore, the performance of HbA1c for diagnosing diabetes and prediabetes was poor. HbA1c should be used in combination with traditional glucose criteria when detecting and diagnosing diabetes or prediabetes.

Palmitate induces autophagy in pancreatic ß-cells via endoplasmic reticulum stress and its downstream JNK pathway.

Endoplasmic reticulum (ER) stress and autophagy have both been reported to be associated with lipotoxicity in ß-cells, yet the relationship between them has not been fully clarified. In the present study, we tested the hypothesis that the ER stress-autophagic pathway in ß-cells is a downstream pathway activated following saturated fatty acid treatment. Mouse insulinoma (MIN6) ß-cells were treated with either palmitate or thapsigargin (TG) with or without various inhibitors. The results indicated that palmitate strongly enhanced the protein expression of microtubule-associated protein 1 light chain 3 (LC3)-II. Furthermore, the expression levels of ER stress markers, BiP and CHOP, and phosphorylation levels of JNK were increased after palmitate treatment. In addition, palmitate-induced autophagy was blocked by 500 µM of the ER stress inhibitor tauroursodeoxycholic acid (TUDCA) or 20 µM JNK inhibitor SP600125. In turn, the phosphorylation of Akt (Ser473) was also downregulated by palmitate, while the levels of insulin receptor ß (IRß) were not reduced. A further increase in LC3-II levels was observed in cells treated with both palmitate and 50 µM PI3K/Akt inhibitor LY294002 compared with cells treated with palmitate alone. Palmitate-induced phospho-Akt (Ser473) downregulation was also inhibited by TUDCA or SP600125. Pretreatment with the autophagy inhibitor 3-methyladenine (3-MA, 5 mM) for 1 h increased the expression of ER stress markers, and enhanced cell injuries caused by 0.1 µM TG, including decreased cell viability and insulin secretion. Palmitate induces autophagy in pancreatic ß-cells possibly through activation of ER stress and its downstream JNK pathway. Palmitate-induced autophagy may protect ß-cells against cell injuries caused by ER stress.

Inhibitory effects of salvianolic acid B on apoptosis of Schwann cells and its mechanism induced by intermittent high glucose.

AIMS: To investigate protective effects of Salvianolic acid B (Sal B) on the intermittent high glucose (IHG)-induced oxidative stress, mitochondrial pathway activation and Schwann cell (SC) apoptosis in vitro. MAIN METHODS: SCs were primarily cultured and exposed to the different conditions. Apoptosis was confirmed by the Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method and concentration of 8-hydroxy-2-deoxy Guanosine (8-OHdG) was detected by Elisa. Intracellular ROS generation and mitochondrial transmembrane potential (ΔΨm) were detected by flow cytometry analysis. Quantitative real-time reverse transcriptase PCR was performed to analyze the expression levels of Bax and BcL-2. Western blot was performed to analyze the expression levels of some important transcription factors and proteins. KEY FINDINGS: Treatment with Sal B inhibited the IHG-induced oxidative stress by reducing ROS production and 8-OHdG levels, mitochondrial depolarization and apoptosis in SCs in a dose-dependent manner. Furthermore, treatment with Sal B down-regulated the IHG-induced release of cytochrome c, AIF nuclear translocation and Bax expression, but mitigated the IHG-mediated down-regulation of BcL-2 expression in SCs. In addition, treatment with Sal B attenuated the IHG-induced activation of caspase-9 and caspase-3 and minimized the cleavage of PARP in SCs. SIGNIFICANCE: Our results indicated that IHG induced SC apoptosis in both caspase-dependent and caspase-independent pathways by activating the mitochondrial pathway. Sal B inhibited the IHG-induced oxidative stress, activation of the mitochondrial pathway and apoptosis in SCs.

[Clinical study of glycated albumin measurement by enzymatic method in type 2 diabetes mellitus].

OBJECTIVE: To evaluate the clinical significance of glycated albumin (GA) measured by enzymatic method and to compare its effect with glycosylated hemoglobin A1c (HbA1c) in type 2 diabetes mellitus (DM). METHODS: 128 type 2 DM patients and 84 normal subjects from the Chinese PLA General Hospital were enrolled for the study. The levels of GA, HbA1c, FBG, PBG in DM patient were detected at baseline and followed visit at 2, 4, 8 weeks after blood glucose management. The levels of GA, HbA1c, FBG, PBG and 75 g OGTT were also detected in above normal subjects. RESULTS: Intra CV and inter CV of enzymatic were (0.74-0.9)% and (0.94-1.49)% respectively. In normal subjects GA was in the range of (9-14)%. At baseline, the GA level was significantly correlated with HbA1c (r = 0.8326, P < 0.01), FBG and 2 hour PBG. After 2, 4, 8 weeks treatment, GA level in DM patients was concomitantly decreased with the improvement of FBG, PBG and HbA1c. At early 2 weeks visit, GA, but not HbA1c, showed significant decrease from its baseline (P < 0.05). CONCLUSION: Enzymatic measuring GA was highly correlated with HbA1c, and changing concomitantly with the decrease of HbA1c, FBG, PBG during the 8 weeks treatment. GA was more sensitive than HbA1c for short-term variations of glycemic control during treatment of diabetic patients. GA can be used as a better index of short term mean level of blood glucose in diabetic patients.

[The relationship between metabolic control and the plasma total homocysteine in type 2 diabetes treated with insulin].

OBJECTIVE: To study the relationship between metabolic control and the plasma total homocysteine (tHcy) in type 2 diabetes treated with insulin. METHODS: A total of 68 patients with type 2 diabetes were recruited. At baseline and the end of 3 month therapy, fasting blood samples were collected for measuring fasting blood glucose (FBG), HbA1c, tHcy and other routine biochemical testing and postprandial blood was collected to measure postprandial blood glucose (PBG). RESULTS: FBG, PBG and HbA1c decreased significantly (P < 0.01) after 3 month intensive insulin therapy. tHcy also decreased, but the decrease did not reach statistic significance (P > 0.05). 7.0% of HbA1c was selected as the cut point judging the level of metabolic control. The HbA1c level was less than 7.0% in 31 (45.6%) patients after insulin treatment alone. In these patients, FBG, PBG and HbA1c significantly decreased, when compared with those of pre-treatment. The plasma tHcy decreased significantly as well. CONCLUSIONS: After insulin treatment, the plasma tHcy decreases when the metabolic control is improved significantly.

[The impact of pioglitazone on plasma homocysteine high-fat diet-induced insulin resistance in rats].

OBJECTIVE: To study the effect of pioglitazone on plasma homocysteine in insulin resistant rats induced by high-fat diet. METHODS: 24 Wistar rats were randomized into 3 groups: a control group (n = 8) was fed with normal feeds. High-fat diet was given to a high-fat group and a pioglitazone group. Pioglitazone (10 mg/kg) was then administered by gavage daily for 11 weeks to the pioglitazone group. At week 11, glucose tolerance test was performed, and serum insulin, fasting glucose and plasma homocysteine were detected. Visceral adipose was weighted and then the ratio of visceral adipose over body weight calculated. RESULTS: Fasting glucose, fasting insulin, insulin resistance index (HOMA IR), and the visceral adipose were significantly different among the 3 groups. Fasting glucose, fasting insulin, HOMA IR, and visceral adipose were all significantly lower in the pioglitazone group than those in the high fat group (P < 0.01). Plasma homocysteine decreased significantly in the pioglitazone-treated rats [(8.8 +/- 1.39) micromol/L] as compared with the other two groups [control group: (9.95 +/- 2.40) micromol/L and high fat group: (35.7 +/- 14.1) micromol/L]. Correlation analysis showed that fasting glucose, fasting insulin, HOMA IR and visceral adipose were all factors influencing the plasma homocysteine. Stepwise regression test showed only fasting glucose (r = 0.504, P = 0.031) and HOMA IR (r = 0.302, P = 0.046) independently affected the level of plasma homocysteine. CONCLUSION: It is concluded that pioglitazone can lower plasma homocysteine in insulin resistant Wistar rats induced by high-fat diet.

[The mechanism of homocysteine in Kkay mice diabetic nephropathy model].

OBJECTIVE: To study the expression of matrix metalloproteinase-9 (MMP-9) in diabetic nephropathy of Kkay mice with hyperhomocysteinemia. METHODS: Sixteen Kkay mice were divided into two groups with 8 in each:diabetes group (KA) and methionine-diet group (KB). C57BL/6 mice were used as normal control (C57). Four months after being treated with two different diets, the mice were sacrificed and serum homocysteine (Hcy) was assayed with fluorescence polarization immunoassay. Renal pathological change was examined with periodic acid Schiff (PAS). The expression of MMP-9 protein and mRNA was detected with immunohistochemical staining and reverse transcriptase-PCR respectively. RESULTS: It was shown that induction of hyperhomocysteinemia in Kkay mice (KB) with a diet enriched in methionine aggravated diabetic nephropathy as compared with the KA group (P < 0.05). The expression of MMP-9 protein and mRNA in KB group was also enhanced and the mean positive area of MMP-9 in KB group was higher than that in KA group (15.90% vs 11.14%, P < 0.05). CONCLUSION: The increased level of Hcy could worsen the nephropathy; this may be related to a higher expression of MMP-9.