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Background and aims: Glycated hemoglobin A1c (HbA1c) ≥6.5% (or 48mmol/mol) has been recommended as a new diagnostic criterion for diabetes; however, limited literature is available regarding the effect of age on the HbA1c for diagnosing diabetes and the causes for this age effect remain unknown. In this study, we investigated whether and why age affects the diagnostic efficiency of HbA1c for diabetes in a community-based Chinese population. Methods: In total, 4325 participants without previously known diabetes were enrolled in this study. Participants were stratified by age. Receiver operating characteristic curve (ROC) was plotted for each age group and the area under the curve (AUC) represented the diagnostic efficiency of HbA1c for diabetes defined by the plasma glucose criteria. The area under the ROC curve in each one-year age group was defined as AUCage. Multiple regression analyses were performed to identify factors inducing the association between age and AUCage based on the changes in the β and P values of age. Results: The current threshold of HbA1c (≥6.5% or 48mmol/mol) showed low sensitivity (35.6%) and high specificity (98.9%) in diagnosing diabetes. ROC curve analyses showed that the diagnostic efficiency of HbA1c in the ≥75 years age group was significantly lower than that in the 45–54 years age group (AUC: 0.755 vs. 0.878; P<0.001). Pearson correlation analysis showed that the AUCage of HbA1c was negatively correlated with age (r = -0.557, P = 0.001). When adjusting the red blood cell (RBC) count in the multiple regression model, the negative association between age and AUCage disappeared, with the regression coefficient of age reversed to 0.001 and the P value increased to 0.856. Conclusions: The diagnostic efficiency of HbA1c for diabetes decreased with aging, and this age effect was induced by the decreasing RBC count with age. HbA1c is unsuitable for diagnosing diabetes in elderly individuals because of their physiologically decreased RBC count. [ABSTRACT FROM AUTHOR]

Background/Objectives: Vitamin D exerts metabolic activities. We investigated whether the 25-hydroxy vitamin D [25(OH)D] is associated with liver fat content (LFC) and non-alcoholic fatty liver disease (NAFLD) in a middle-aged, elderly Chinese population. Subject/Methods: A total of 2,960 participants (954 men and 2,006 women) aged over 45 years old were enrolled. Each participant underwent a standard interview, anthropometric measurements and laboratory examinations. Vitamin D deficiency and insufficiency was diagnosed when serum 25(OH) D level was < 50 and 50–75nmol/L. An ultrasound quantitative method was used to assess the LFC. Results: Among the 2,960 participants, 1,982 (67.0%) subjects had vitamin D deficiency, 769 (26.0%) had vitamin D insufficiency, and 209 (7%) had normal vitamin D. Male subjects with vitamin D deficiency and insufficiency had significantly higher LFC than those with normal 25(OH)D (P = 0.034), while the LFC values showed no significant difference among the female subjects with vitamin D sufficiency, insufficiency and deficiency (P = 0.396). Univariate correlation analysis showed that 25(OH)D had a significantly negative association with LFC in men (r = -0.085, P = 0.009), but not in women. After adjusting for age, cigarette smoking, examination season, serum calcium, PTH and all possible confounders that displayed significant associations with LFC in univariate correlation analysis, serum 25(OH)D remained associated with LFC in middle-aged and elderly Chinese men. Conclusion: Serum 25(OH)D level was inversely associated with LFC in middle-aged and elderly Chinese men. [ABSTRACT FROM AUTHOR]

Abstract: Background: Nonalcoholic fatty liver disease is closely associated with metabolic syndrome and cardiovascular disease (CVD). We investigated whether the liver fat content (LFC) is independently associated with carotid artery intima-media thickness (CIMT) and evaluated the contribution of the LFC to the increased CIMT. Methods: We conducted a community-based study among 1809 participants (682 males and 1127 females) from the Changfeng Study who were at least 45 years old. A standard interview, anthropometrics and laboratory parameters were performed for each participant. The CIMT was determined by ultrasonography. A large CIMT value was defined as 75th percentile of the maximum CIMT. A standardised ultrasonographic hepatic-renal ratio was used to assess the LFC. Results: The median LFC value was 6% (interquartile range, 3–14%), and 34% of the subjects had hepatic steatosis based on the criteria for diagnosis of steatosis by quantitative ultrasound. The maximum CIMT, average CIMT and plaque score were strongly associated with the LFC (β = 0.319, 0.324 and 1.361, respectively; all P < 0.05) after adjustment for age, gender, smoking history, low-density lipoprotein cholesterol and metabolic syndrome. The multiple logistic regression analysis showed that a 1 SD increase in the LFC, the OR for having a large CIMT was 1.350 (95% CI 1.180–1.545; P < 0.001) after adjustment for all potential confounders. Conclusions: These results suggest that the LFC is independently associated with carotid atherosclerosis in the Chinese population, and that the risk of atherosclerosis is proportional to the degree of hepatic steatosis. [Copyright &y& Elsevier]