Asian patients comprise greater than 8% of our diabetic clinic. Retrospective analysis of the case notes of 22 Asian patients and 20 white patients with NIDDM or impaired glucose tolerance (IGT) attending our combined diabetic/antenatal clinic during 1985-1987 confirmed the reported advantages of pre-conception counselling. Those Asian patients with NIDDM or IGT had higher corrected birthweight than a parity matched Asian control group (3,472.3 +/- 595 g v 2,798.6 +/- 672.3 g p less than 0.001). Those Asian patients who had preconception counselling had, however, significantly smaller babies (3,270.8 +/- 445.1 g v 3,714.4 +/- 727.1 g p less than 0.05). An increase in foetal and maternal complications has been documented in cases of gestational diabetes, but the glucose levels that predict an increased risk have not been clearly defined. In the Asian patients with NIDDM/IGT there was one neonatal death and two congenital abnormalities, although these mothers did not have significantly higher glycosylated haemoglobin levels. HbA1 was not a good diagnostic test for glucose tolerance. Subjects with any degree of glucose intolerance should be managed as carefully as established diabetics and preconception counselling for high risk groups may be beneficial.