Is leptin associated with diabetic retinopathy?
OBJECTIVE
In advanced stages of diabetic retinopathy, new blood vessels are formed based on undefined mechanisms. Recently, leptin was shown to possess an angiogenic action in vitro and to induce neovascularization in vivo. The aim of the present study was to investigate the relationship between plasma leptin levels and the severity of diabetic retinopathy.


METHODS
There were 70 patients with type 2 diabetes (age 47.9 +/- 9.7 years, BMI 26.4 +/- 3.3 kg/m2) who were seen in a retina outpatient clinic recruited and assigned to subgroups according to the stage of their diabetic retinopathy. There were 66 healthy volunteer subjects matched with the diabetic patients for age, BMI, and sex who served as control subjects (age 46.0 +/- 8.8 years, BMI 27.1 +/- 2.3 kg/m2). Fasting plasma leptin levels were measured.


RESULTS
Plasma leptin level of the diabetic patients was not significantly different from the control subjects. In patients with proliferative diabetic retinopathy (n = 17), the mean plasma level of leptin (16.1 +/- 9.2 ng/ml) was significantly higher than that in patients with nonproliferative retinopathy (n = 20) (11.5 +/- 3.5 ng/ml, P = 0.039) or patients without retinopathy (n = 33) (5.8 +/- 3.7 ng/ml, P = 0.001). The mean leptin level in patients with nonproliferative diabetic retinopathy was also significantly higher than that in patients without retinopathy (P = 0.002).


CONCLUSIONS
Our results show that the more advanced the diabetic retinopathy, the higher the plasma leptin levels, even after adjusting the leptin levels for BMI. The presence of such a positive correlation need not imply a causal relationship. Nevertheless, previously observed leptin-induced promotion of angiogenesis and neovascularization lends support to the possibility that leptin may play a role in the progression of human diabetic retinopathy to a proliferative phase. This possibility deserves further investigation.
Uckaya
G
G
Department of Endocrinology and Metabolism, Gulhane School of Medicine, Etlik/Ankara, Turkey.
Ozata
M
M
Bayraktar
Z
Z
Erten
V
V
Bingol
N
N
Ozdemir
I C
IC
D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D003404:Creatinine / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000097:blood* / Q000145:classification; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012016:Reference Values
D015415:Biomarkers; D001786:Blood Glucose; D003404:Creatinine; D006442:Glycated Hemoglobin; D020738:Leptin