Insulin-like growth factor-I投与後に増悪した糖尿病網膜症の1例

Exacerbation of diabetic retinopathy following systemic insulin-like growth factor-I. Report of a case

　A型インスリン受容体異常症に合併した増殖糖尿病網膜症について報告した。症例は19歳の女性で，先天的なインスリン受容体の異常のため，高インスリン血症とインスリン投与に抵抗する高血糖があった。インスリンと類似の血糖降下作用のあるInsurin-Like growth factor-I（IGF-I）の投与により，血糖値は低下した。IGF-Iの投与前には糖尿病網膜症はみられなかったが，投与開始後5か月に網膜出血が出現し，7か月目から眼底に新生血管が発生した。網膜光凝固を行ったが，増殖性変化が鎮静化しないため，IGF-Iの投与を中止した。中止後速やかに新生血管は消退傾向を示し，投与中止後3か月には認められなくなった。この症例において，IGF-Iが血糖値を降下させると同時に，網膜血管内皮細胞の増殖促進にも影響を及ぼしていたことが示唆された。

A 19-year-old female had been diagnosed as diabetes mellitus 8 years before. She was identified as type A insulin resistance syndrome. She had hyperinsulinemia and hyperglycemia due to defect in the insulin receptor gene. She was given insulin-like growth factor-I (IGF-I). No retinopathy was present then. The blood sugar level decreased smoothly. Seven months after initiation of the treatment, proliferative retinopathy started to progress. Panretinal photocoagulation failed to prevent disc and retinal neovascularizations. Withdrawal of IGF-I was followed by rapid disappearance of neovascularizations. It appeared that IGF-I decreased the blood sugar level by its insulin-like effect and that it also induced fundus neovascularizations by its growth hormone-like effect on endothelial cells of retinal vessels.