A trial of simple versus intensified dietary modification for prevention of progression to diabetes mellitus in women with impaired glucose tolerance

Women with impaired glucose tolerance are at high risk of developing nonins ulin dependent diabetes mellitus (NIDDM). The Mercy Hospital fur Women has a long-term follow-up programme for women with gestational diabetes, which identifies many women with impaired glucose tolerance. Two hundred of these women were entered into a randomized controlled trial of intensive versus routine dietary advice. Seven women were lost to follow-up. The annual inci dence rates of diabetes mellitus for the 2 groups were 6.1% (intervention) and 7.3% (control), an incident rate ratio of 0.83, 95% confidence interval 0.47-1.48, p = 0.50. Overall, there was a return to normal glucose toleran ce in 44% of patients. Multivariate analysis showed that body mass index, f asting and 2-hour plasma glucose levels at trial entry were significantly a ssociated with an increased risk of diabetes mellitus. Impaired glucose tol erance is an important condition that should be treated with advice about l ifestyle modification (diet and/or exercise). We consider that future trial s in the management of women with previous gestational diabetes who have im paired glucose tolerance should investigate the effect of pharmacological i ntervention in addition to diet and/or exercise, the latter providing a the rapy that it would be unethical to exclude on the evidence presently availa ble.