[The renal protective effect and mechanism of liraglutide in diabetic mice induced by high-fat diet].

Objective: To investigate the protective effect of liraglutide on kidney of diabetic mice induced by high-fat diet and its possible mechanisms. Methods: C57BL/6J male mice were randomly divided into normal chow diet (NC) group and high-fat diet (HFD) group, which were fed with normal chow diet and HFD for 12 weeks respectively. After diet challenge, the mice were randomly divided into normal control group, normal chow diet with liraglutide treatment (NC+Lira) group, HFD group and high-fat diet with liraglutide treatment (HFD+Lira) group. The mice in NC+Lira and HFD+Lira groups were given intraperitoneal injection of liraglutide (400 µg·kg(-1)·d(-1)) for 8 weeks, while mice in NC and HFD groups were given intraperitoneal injection of same amount of normal saline. Urinary albumin and creatinine levels were measured by enzyme-linked immunosorbent assay (ELISA). Renal morphology was observed by HE staining. The expression levels of silent mating type information regulation 2 homolog 1 (SIRT1) and thioredoxin-interacting protein (TXNIP) were determined by Western blot. Results: Compared with HFD group, liraglutide significantly lowered the body weight [(30.98±1.29) g vs (39.43±2.58) g], fasting blood glucose (FBG) [(7.21±0.15) mmol/L vs (9.55±0.29) mmol/L] and urinary albumin/creatinine ratio (ACR) [(205.48±17.14) µg/mg vs (319.86±34.14) µg/mg] in HFD+Lira group (all P<0.05). HE staining showed that glomerular hypertrophy of HFD group alleviated after liraglutide treatment. The expression level of TXNIP in the kidney of HFD mice significantly decreased after liraglutide treatment (0.41±0.10 vs 3.50±0.70), while expression level of SIRT1 significantly increased (0.75±0.15 vs 0.32±0.04) (both P<0.05). Conclusion: Liraglutide could improve diabetic nephropathy by up-regulation of SIRT1 expression and down-regulation of TXNIP expression in diabetic mice induced by HFD.

[Utility of hemoglobin A1c for diagnosing metabolic syndrome in Chinese subjects over 50 years old].

Objective: To evaluate glycated hemoglobing A1c (HbA1c) in diagnosing metabolic syndrome (MS) in Chinese subjects aged over 50 years. Methods: A community-based cross-sectional survey was conducted between October 2010 and January 2011 in Shipai community, Guangzhou. A total of 1 494 subjects aged over 50 years were investigated. Questionnaire survey and physical examination were performed among all participants. Fasting blood samples were obtained to measure plasma glucose (FPG), blood lipids and HbA1c. MS was defined by the criteria of International Diabetes Federation (IDF), National Cholesterol Education Program-Adult Treatment Panel Ⅲ (ATP Ⅲ)(2005) and Chinese Diabetes Society (CDS), respectively. Receiver operating characteristic (ROC) curves were plotted to explore the accuracy of HbA1c for diagnosing MS. Results: After excluding subjects with missing data, the remaining 1 473 subjects had a median age of 61 years (55-68 years). An HbA1c threshold of 6.1% yielded the highest combination of sensitivity (52.1%) and specificity (84.3%) for diagnosing MS. Using HbA1c≥5.7% as definition of dysglycemia, the prevalence of MS (IDF), MS (ATP Ⅲ) and MS (CDS) were 48.7%, 57.1% and 50.8%, respectively. The κ coefficients were 0.853, 0.768 and 0.730, respectively. Using HbA1c≥6.1% as definition of dysglycemia, the prevalences of MS (IDF), MS (ATP Ⅲ) and MS (CDS) were 41.2%, 45.8% and 39.1%, respectively. The κ coefficients were 0.923, 0.880 and 0.881, respectively. The optimal HbA1c threshold with the highest level of agreement according to IDF, ATP Ⅲ and CDS criteria were 6.1%, 6.3% and 6.3%, respectively. Conclusions: An HbA1c threshold of 6.1% showed a high specificity for diagnosing MS in Chinese subjects aged over 50 years in community-based setting. The optimal HbA1c threshold may vary according to different criteria and populations.