Gycosuria as an indication for glucose tolerance testing during pregnancy.

The indications for and results of all glucose tolerance tests (GTTs) performed at the Antenatal Clinic, Groote Schuur Hospital, Cape Town, over a period of 1 year, and the indications for a GTT in the first 80 newly diagnosed diabetics over a 4-year period are analysed. Out of 558 GTTs, only 17 tentative diagnoses of 'gestational diabetes' were made. The most rewarding single indication for a GTT was repeated glycosuria, which was an indication in 61 out of the 80 newly diagnosed diabetics. A combination of two indications in the same patient was related to twice as many abnormal GTTs as a single indication, while reported previous diabetes or hyperglycaemia certainly merited confirmation. Reasons for repeating GTTs are discussed, as well as the management of 'borderline' and 'potential' diabetics. It is emphasized that 'diabetes' or 'hyperglycaemia' diagnosed during pregnancy is not equivalent to a definite diagnosis of diabetes in the non-pregnant state.