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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. [ABSTRACT FROM AUTHOR]

Background: Serum creatinine is the most widely used marker for estimating glomerular filtration rate (GFR). The aim of this study was to determine pédiatrie 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 x age (year) + 0.5, where k was 0.03 for boys and 0.02 for girls. Conclusions: This study presents pédiatrie 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 m² and 80 - 129 mL/min/1.73 m², respectively. These values can be used for diagnostic and therapeutic purposes. [ABSTRACT FROM AUTHOR]

Background: Vitamin D (vit D) affects glucose metabolism. Receptors of vitamin D have been identified in β cells and studies show that vitamin D deficiency reduces glucose-stimulated insulin secretion (GSIS)., Objectives: The aim of this study was to examine the effect of vitamin D on insulin release from isolated islets of rats., Materials and Methods: Islets were isolated from male Wistar rats, weighing 200-250 grams, using the collagenase digestion method. Insulin release was assessed following 24 and 48 hours coincubation of islets with vitamin D (0.1, 1 and 10 nM) and glucose (5.6, 11.1 and 16.7 mM). In addition, islets were preincubated with vitamin D for 24 and 48 hours and GSIS was assessed for one hour in the presence of 5.6 and 16.7 mM glucose., Results: Coincubation of islets with vitamin D (10 nM) and 11.1 mM glucose increased islet insulin release (37.27 ± 3.75 vs. 24.64 ± 2.83 ng/islet/24 hours; P < 0.05), while vitamin D (1 and 10 nM) decreased insulin release in the presence of 16.7 mM glucose (21.14 ± 3.58 and 18.65 ± 3.84 vs. 37.71 ± 4.63 ng/ islet/24 hours; P < 0.05). Islets preincubation with vitamin D (1 and 10 nM) increased GSIS in the presence of 16.7 mM glucose (4.39 ± 0.73 and 4.39 ± 0.63 vs. 2.07 ± 0.43 ng/islet/1 hour; P < 0.05)., Conclusions: Preincubation of islets with vitamin D increased GSIS but decreased insulin release in coincubation with high levels of glucose. Insulin secretion from β cells in the presence of glucose seems to be related to the dosage of vitamin D and duration of preincubation.