AIMS—To assess the prevalence of dysthyroid optic neuropathy (DON) in patients with diabetes mellitus (DM) and Graves' orbitopathy (GO) and to investigate the complications of surgery for GO in these patients. METHODS—The records of 482 consecutive patients with GO referred in a 5 year period were studied. Those patients who also had DM were selected for further study. The prevalence of insulin dependent diabetes mellitus (IDDM) and non-insulin dependent diabetes mellitus (NIDDM) was registered, as well as the prevalence and course of DON. In the patients who underwent surgery for GO the postoperative complications were recorded. RESULTS—Out of 482 patients with GO, 15 (3.1%) also had DM. Eight (1.7%) had IDDM, 7 (1.4%) had NIDDM. Five patients (33.3%) three with IDDM and two with NIDDM developed DON with 50% improvement of visual acuity after treatment, whereas in the whole population of 482 GO patients 19 had DON (3.9%), showing 69.4% improvement of vision after treatment. 10 patients with GO and DM were operated for GO; in one of them an optic atrophy developed as a result of a postoperative haemorrhage directly after a three wall orbital decompression by coronal approach. No other postoperative complications occurred. CONCLUSIONS—The prevalence of IDDM in patients with GO is higher than in the normal population. DON occurs much more frequently in patients with GO and DM than in the total group of GO patients and seems to have a worse visual prognosis.
