Serum levels of adiponectin are associated with diabetic retinopathy and with adiponectin gene mutations in Caucasian patients with diabetes mellitus type 2.

INTRODUCTION: Even diabetic patients with excellent glycemic control can develop diabetic complications very early. Possibly, not only the degree of glycemic control, but other factors as well are responsible for the development of diabetic microangiopathy. Since adiponectin represents an adipocyte-specific secretory protein modulating endothelial cell functions, it was the aim of the present study to investigate the role of adiponectin serum levels as well as adiponectin gene polymorphisms in the development of diabetic retinopathy.
METHODS: A population based cohort of caucasian patients (n=523) with type 2 diabetes mellitus was recruited from an epidemiological field survey. Serum adiponectin levels were determined by ELISA. Genotypes of the Tyr111His and the Gly15Gly polymorphism were determined by PCR-based RFLP analysis. Diabetic retinopathy was graded by fundus photography.
RESULTS: The data demonstrate, that a) the Tyr111His (T-->C) polymorphism influences adiponectin serum levels, b) adiponectin serum levels do correlate with the prevalence of diabetic retinopathy, and c) patients heterozygous for the +45 T-->G (Gly15Gly) polymorphism show a lower prevalence of diabetic retinopathy. Furthermore, we could generate the proof of principle that adiponectin is detectable in the fluid of the human vitreous body.
SUMMARY: Adiponectin gene polymorphisms influence adiponectin serum levels and elevated adiponectin serum levels are associated with diabetic retinopathy in patients with diabetes mellitus type 2. Therefore, endothelial cell modulating adiponectin should be further investigated as a candidate gene in the development and progression of retinopathy associated with type 2 diabetes mellitus.