Are serum nitric oxide metabolites associated with fasting insulin among Iranian adults? (Tehran Lipid and Glucose Study).

AIM: It has been suggested that insulin resistance is associated with altered nitric oxide (NO) homeostasis. There is however no population-based study documenting an association between fasting serum insulin and serum NO metabolites (NOx) with multivariable adjustment. This study was therefore designed to determine the association between serum NOx and fasting insulin levels and insulin resistance/sensitivity indices in a sample of a population-based study in Iran. MATERIALS AND METHODS: This study, performed within the framework of the Tehran Lipid and Glucose Study (TLGS), analyzed the data of 1518 non-diabetic subjects (955 women), aged 20-87 years, who had participated in phase III of the TLGS (2006-2008). Serum NOx concentrations were measured using the Griess method. Fasting serum insulin was measured by the electrochemiluminescence immunoassay method. Multiple regression analysis was used to determine the association between serum NOx concentration and quartiles of insulin and insulin resistance/sensitivity indices (HOMA1-IR, HOMA2-IR, and QUICKI). RESULTS: NOx concentration in women only was weakly correlated with HOMA1-IR (r = 0.07, P = 0.03) and QUICKI (r = -0.07, P = 0.03), whereas no significant association was observed in men (P > 0.05). Marginally significant correlations were also found between serum NOx and fasting insulin concentration (r = 0.062, p = 0.057) and HOMA2-IR (r = 0.063, p = 0.053) in women. NOx concentration differed significantly between quartiles of insulin and insulin resistance/sensitivity indices among women and the total population (P < 0.05), associations which remained significant after age adjustment (P < 0.05), but not after adjustment for other confounding variables (P > 0.05). CONCLUSIONS: Fasting serum insulin level and insulin resistance/sensitivity indices are not associated with serum NOx level after multivariable adjustment.

Seven-Year Changes of Leisure-Time and Occupational Physical Activity among Iranian Adults (Tehran Lipid and Glucose Study).

BACKGROUND: Considering the lack of data available on changes of physical activity over time in Iran, this study was designed to evaluate changes in physical activity levels among Iranian adults over a median 6.5 yr period. METHODS: In this population-based cohort study, 3515 participants, aged ≥ 20 yr (2100 females and 1415 males) were followed from phase II (2002-2005) to phase IV (2008-2011) of the Tehran Lipid and Glucose Study. Information on physical activity, both leisure time (LTPA) and occupational (OCPA), was collected using the Modifiable Activity Questionnaire. Scores ≤600 METs-min/wk were considered as having low physical activity. Wilcoxon test was performed for comparing MET values between the two phases. McNemar test was used to evaluate differences between paired qualitative data. RESULTS: In both phases, 59.8% of adults were women, with mean±SD age 44.3±14.6 and 50.9±14.6 yr, in phases II and IV respectively. The prevalence of low physical activity decreased significantly in the follow up period (from 45.9% in phase II to 42.6% in phase IV, P=0.004). In both genders, a non-significant decrease in OCPA was observed, However, there was a significant decrease in LTPA among women (P=0.031), but not in men. CONCLUSION: Despite the high levels of physical activity in Tehranian adults, a decreasing trend was observed. Significant decrease in LTPA among women indicates the urgent need to target women for prevention and implementation of public educational programs to promote physical activity levels and LTPA in particular, to compensate the reduction in OCPA.

Pediatric reference values for serum creatinine and estimated glomerular filtration rate in Iranians: Tehran Lipid and Glucose Study.

BACKGROUND: Serum creatinine is the most widely used marker for estimating glomerular filtration rate (GFR). The aim of this study was to determine pediatric reference values for serum creatinine levels and eGFR values using data from a population-based study in Iran. METHODS: Serum creatinine of 1594 subjects, aged 3 - 18 years, participating in phase 4 of the Tehran Lipid and Glucose Study (2008 - 2011) was measured using the conventional Jaffe method. The non-parametric method of Schwartz and Counahan-Barratt equations were used to calculate eGFR. CLSI/IFCC guidelines were used to determine reference values. RESULTS: In both genders, serum creatinine concentration was significantly increased with age and had a positive correlation with age (boys (r = 0.786, n = 778, P < 0.001) and girls (r = 0.638, n = 724, P < 0.001)). In addition, mean serum creatinine concentration was significantly higher in boys, compared to girls (0.86 ± 0.01 vs. 0.80 ± 0.01 mg/dL, P < 0.001). Based on these results, we proposed the following formula: serum creatinine (mg/dL) = k × age (year) + 0.5, where k was 0.03 for boys and 0.02 for girls. CONCLUSIONS: This study presents pediatric reference values in Iranian boys and girls for serum creatinine levels to be 0.6 - 1.20 mg/dL and 0.6 - 1.00 mg/dL and for eGFR values to be 81 - 154 mL/min/1.73 m(2) and 80 - 129 mL/min/1.73 m(2), respectively. These values can be used for diagnostic and therapeutic purposes.