Hypoglycaemia in Clinical Diabetes

CLINICAL MANAGEMENT BEFORE AND DURING PREGNANCY 227Table 10.3Maternal issues in pregnancyDiabetes-relatedHypoglycaemiaIncreased risk of ketoacidosisRetinopathy may deteriorateNephropathy and fluid retentionPre-eclampsia/hypertensionIncreased caesarean section rateObstetricPreterm deliveryIncreased caesarean section rateMacrosomia and shoulder dystociaassigned to conventional treatment, the occurrence of hypoglycaemia resulting in impairedconscious level was 4.0 per 100 pregnant-months compared with 2.8 in those receivingintensive treatment. Those women in the conventional group who had changed to intensivetherapy before conception experienced significantly fewer episodes of hypoglycaemia duringpregnancy than those who had not intensified their regimen until after conception (2.0 versus5.0 episodes per 100 patient years). This suggests that it may be preferable, where possible,to intensify the insulin regimen during the pre-pregnancy period rather than making thechange once conception has occurred.Another study of 118 women with pre-gestational diabetes compared twice daily freemixing of soluble and isophane insulins with a basal-bolus regimen of soluble insulinbefore meals and bedtime isophane insulin (Nachum et al., 1999). The authors reported nodifference between the regimens in the incidence of hypoglycaemia, although those takingfour injections of insulin per day achieved better glycaemic control. One interpretation ofthe data is that the greater the insulin dosage, the better the glycaemic control. However, theoverall incidence of recorded hypoglycaemia was remarkably low (10%) and almost half thewomen had type 2 diabetes.Short-acting insulin analogues have received some attention and one randomised trial ofinsulin lispro in pregnancies complicated by type 1 diabetes has been reported (Perssonet al., 2002). Thirty-three women were studied with 16 being randomised to lispro and 17 tosoluble insulin at gestational week 15. Most of the women had very good glycaemic controlat entry to the study (mean HbA 1c 6.5%, range 4.5–8.6%). Only two patients experiencedsevere hypoglycaemia during the remainder of their pregnancies and both were on humansoluble insulin, although it is important to remember that the study was undertaken inthe latter half of pregnancy when the risk of hypoglycaemia is usually lower. However, asignificantly higher rate of biochemical hypoglycaemia (< 30 mmol/l) was documented inthe women using lispro (who were monitoring blood glucose six times daily). No differenceswere observed between the groups with regard to glycated haemoglobin, although womentaking lispro had lower postprandial glucose excursions. In an observational study in whichwomen received lispro before and during pregnancy, the prevalence of severe hypoglycaemiawas 23%, with no greater incidence of adverse outcomes compared to other regimens(Garg et al., 2003). A similar prospective study that was designed to assess progressionof retinopathy during pregnancy in women on lispro, demonstrated that the number ofsubjective hypoglycaemic events did not differ between those taking lispro and those takingsoluble insulin, although the overall rates of hypoglycaemia were relatively low (Loukovaaraet al., 2003).