Glucose tolerance and glycosuria in Ethiopian porphyria cutanea tarda patients.

Oral glucose tolerance test (OGTT) was performed in 50 Ethiopians with proven porphyria cutanea tarda (PCT) in 30 of whom urine sugar was also checked. The result of the OGTT, interpreted according to WHO criteria, showed that 35 (70%) patients had normal OGTT, 14 (28%) impaired glucose tolerance (IGT) and 1 diabetes mellitus. Seven patients with IGT, the diabetic and one with normal OGTT had glycosuria of variable degree during the OGTT; none had fasting glycosuria. The patient with diabetes and one other with IGT later on developed mild but nonspecific symptoms. In addition, their blood glucose deteriorated further and required the administration of oral agents to control it. The study clearly indicates the association of diabetes with PCT. Since diabetes mellitus may remain asymptomatic in some of the PCT patients, an early diagnosis of the former is likely to be missed unless looked for.