Plasma adiponectin and serum advanced glycated end-products increase and plasma lipid concentrations decrease with increasing duration of type 2 diabetes

Objective: To prospectively follow the concentrations of plasma adiponectin (p-adiponectin) and serum advanced glycation end-products (s-AGE) in relation to plasma lipids and retinopathy over 3 years in type 2 diabetic patients. Design and methods: P-adiponectin, s-AGE, plasma lipids and diabetic retinopathy were prospectively evaluated in 61 type 2 diabetic patients at baseline and at follow up 3 years later. Results: Mean p-adiponectin (from 8.84+/-5.14 to 11.05+/-6.16 mug/ml; P = 0.006) and s-AGE (from 637+/-242 to 781+/-173ng/ml; P < 0.0001) concentrations had increased at follow up. In addition, HbA1c (7.7+/-1.7 to 7.4+/-1.4%; P = 0.0045) and fasting C-peptide (1.00+/-0.38 to 0.81+/-0.35 nM; P = 0.019) had decreased and all lipid variables had significantly improved at follow up. P-adiponectin correlated inversely with fasting C-peptide (r(s) = -0.273; P = 0.045) and low-density lipoprotein (LDL)/high-density lipoprotein (HDL) ratio (r(s) = -0.362; P = 0.011), and directly with plasma HDL cholesterol (r(s) = 0.381; P = 0.005) at follow up. Analysis of variance with adiponectin and s-AGE as dependent variables and fasting C-peptide, plasma HDL and plasma LDL cholesterol as covariates demonstrated that the increase in s-AGE was independent (P = 0.001) and the increase in p-adiponectin dependent on covariate changes (P = 0.862). There was a slight correlation between s-AGE at baseline versus the degree of retinopathy at follow up (r(s) = 0.281; P = 0.0499). Conclusion: Both p-adiponectin and s-AGE increased during the 3 years. The increase in p-adiponectin was explained by improvements in insulin sensitivity and dyslipidaemia, whereas the increase in s-AGE was independent of changes in metabolic covariates. s-AGE increase when the duration of type 2 diabetes increases.