Growth Factors in Proliferative Diabetic Retinopathy
Sixteen young patients with type 1 diabetes mellitus and rapidly progressive severe retinopathy were examined regarding serum levels of growth hormone before and after the i.v. administration of 200 micrograms thyrotropin-releasing hormone (TRH). Serum IGF I, HbA1c, blood pressure, urinary albumin, and serum creatinine levels were also measured. The control group consisted of type 1 diabetic patients matched for age, duration of diabetes and metabolic control with no or minimal background retinopathy. The results show that basal growth hormone levels were above normal in both groups, and that there was a paradoxical increment in growth hormone levels after TRH stimulation (p < 0.05) in patients with severe retinopathy, but the values did not differ from patients with background retinopathy. IGD I levels were normal in all patients but one, and no differences were seen between the two groups. HbA1c, serum creatine, blood pressure, and urinary albumin levels were similar in the groups but patients with severe retinopathy were treated with more insulin (p < 0.001). Thus, neither abnormal growth hormone levels, nor IGF I, seems to be associated with the development of severe retinopathy in young type 1 diabetic patients.