Background: Adiponectin represents an adipocyte-specific secretory protein that has been discussed recently as candidate gene and promising new drug target to restore insulin sensitivity in diabetes mellitus type 2.
Aim: The aim of the present study was to define influencing variables on adiponectin serum levels in a large cohort of caucasian patients with type 1/type 2 diabetes and healthy controls. Additionally, adiponectin gene polymorphisms (Tyr111His and Gly15Gly) were investigated for possible associations with adiponectin serum levels.
Methods: Adiponectin serum concentrations were measured in a metabolically well characterized cohort of 892 caucasian patients (556 with type 2 diabetes, 118 with type 1 diabetes, 218 controls) by ELISA. Gene polymorphisms were determined by PCR-based RFLP.
Results: 1) Adiponectin values are dependent on gender with higher levels in diabetic females than in diabetic males. This gender-specific effect was only restricted to patients with diabetes and cannot be observed in controls. 2) In contrast to previous studies, the presence of diabetes does not influence adiponectin serum levels after correction for BMI. In addition, age has no influence on adiponectin levels. 3) Adiponectin levels are dependent on renal function at a creatinine clearance < 45 ml/min. 4) Regression analysis showed a significant, but only weak correlation between BMI and adiponectin in patients with diabetes mellitus type 2 (r = 0.47) and type 1 (r = 0.57). 5) Adiponectin gene polymorphisms (Tyr111His and Gly15Gly) do not influence adiponectin levels.
Conclusions: Adiponectin serum concentrations can only be interpreted after careful correction for gender and renal function, whereas the genetic variants Tyr11His and Gly15Gly do not seem to play a role. The correlation between BMI and adiponectin was weaker than expected in diabetic patients.