Glycaemic control is associated with pre-eclampsia but not with pregnancy-induced hypertension in women with Type I diabetes mellitus

Aims/hypothesis. To investigate the association between glycaemic control a nd hypertensive pregnancy complications. Methods. From 1988 to 1997, we followed up 683 consecutive non-selected pre gnancies in women with Type I (insulin-dependent) diabetes mellitus. Glycae mic control was assessed by assay of HbA(1c). Pre-eclampsia was defined as diastolic blood pressure of 90 mmHg or more at the end of pregnancy after a n increase of 15 mmHg or more, combined with proteinuria of 0.3 g or more f or 24 h. Pregnancy-induced hypertension was defined similarly but without p roteinuria. The same criteria were applied to a control group of 854 non-se lected non-diabetic women. Results. Pre-eclampsia developed in 12.8% of the women with diabetes (exclu ding those with nephropathy before pregnancy) and in 2.7% of the control wo men (odds ratio 5.2; 95% CI 3.3-8.4). In multiple logistic regression, glyc aemic control, nulliparity, retinopathy and duration of diabetes emerged as statistically significant independent predictors of pre-eclampsia. The adj usted odds ratios for pre-eclampsia were 1.6 (95% CI 1.3-2.0) for each 1% i ncrement in the HbA(1c) value at 4-14 (median 7) weeks of gestation and 0.6 (0.5-0.8) for each 1% decrement achieved during the first half of pregnanc y. Changes in glycaemic control during the second half of pregnancy did not significantly alter the risk of pre-eclampsia. Unlike pre-eclampsia, the r isk of pregnancy-induced hypertension was not associated with glycaemic con trol. Conclusion/interpretation. In women with Type I diabetes, poor glycaemic co ntrol is associated with an increased risk of pre-eclampsia but not with a risk of pregnancy-induced hypertension.