Women with GDM have a greater risk of developing diabetes in the future compared with those women who have normal glucose tolerance during pregnancy. Using life table techniques, 17 years after the initial diagnosis of GDM, 40% of women were diabetic compared with 10% in a matched control group of women who had normal glucose tolerance in pregnancy. The incidence of diabetes was higher among women who were older, more obese, of greater parity and with more severe degrees of glucose intolerance during pregnancy. Diabetes also occurred more commonly among women who had a first-degree relative who was diabetic, in women born in Mediterranean and East Asian countries, and in those who had GDM in two or more pregnancies. Despite differing testing techniques and varying criteria for the diagnosis of GDM, follow-up studies from across the world consistently show a higher rate of subsequent diabetes among GDM mothers. NIDDM is associated with increased morbidity and a higher mortality rate, especially in women. Cardiovascular and cerebrovascular diseases are the leading causes of death. High lipid levels, hypertension and obesity are often already present when diabetes is diagnosed and may antedate the development of overt diabetes; treatment of diabetes at this stage may therefore be too late to prevent complications occurring. A follow-up programme for women with GDM facilitates screening of a group known to be at increased risk of developing diabetes so that the diagnosis can be made before associated risk factors for complications develop. Intervention in the form of counselling regarding cigarette smoking, exercise and a healthy, high-residue, unrefined carbohydrate, low cholesterol diet, given together with weight monitoring, may prevent the onset of both diabetes and its associated cerebrovascular and cardiovascular problems.