Question: Is there any place to monitor glycosulated hemoglobin (HbA1c) in pregnant women with gestational diabetes? Especially in relation to predicting fetal morbidity such as macrosomia/ shoulder dystocia
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Answer: The National Institute for Health and Clinical Excellence (NICE) guideline “Diabetes in pregnancy” (1) makes the recommendations:
“Women with gestational diabetes should be instructed in self-monitoring of blood glucose.
Targets for blood glucose control should be determined in the same way as for women with pre-existing diabetes.” …
“Individualised targets for self-monitoring of blood glucose should be agreed with women with diabetes in pregnancy, taking into account the risk of hypoglycaemia.
If it is safely achievable, women with diabetes should aim to keep fasting blood glucose between 3.5 and 5.9 mmol/litre and 1 hour postprandial blood glucose below 7.8 mmol/litre during pregnancy.
HbA1c should not be used routinely for assessing glycaemic control in the second and third trimesters of pregnancy.”
The report comments that “The GDG’s [Guideline Development Group’s] view is that HbA1c is not a reliable indicator of glycaemic control in the second and third trimesters of pregnancy because of physiological changes that occur in all pregnant women and lead to reduced HbA1c in women without diabetes, meaning that any apparent reduction in HbA1c in women with diabetes during the second and third trimesters of pregnancy does not necessarily indicate improved glycaemic control. HbA1c should, therefore, not be used routinely for assessing glycaemic control in the second and third trimesters of pregnancy. This represents a change in clinical practice to avoid unnecessary and misleading HbA1c measurements.”
(Evidence level IV)
A Cochrane review of “Different techniques of blood glucose monitoring in women with gestational diabetes for improving maternal and infant health” is currently in preparation. (2)
References:
1. Diabetes in pregnancy. National Institute for Health and Clinical Excellence (NICE)
http://www.nice.org.uk/CG063 2008
2. Pelaez-Crisologo MCG, Castillo-Torralba MGAGN, Festin MR. Different techniques of blood glucose monitoring in women with gestational diabetes for improving maternal and infant health (Protocol). Cochrane Database of Systematic Reviews 2009, Issue 2. Art. No.: CD007790. DOI: 10.1002/14651858.CD007790. Full text available here (access restricted in some countries) or to Fellows, Members and Trainees through this link
Search date: July 2009
Classification of evidence levels
Ia Evidence obtained from meta-analysis of randomised controlled trials.
Ib Evidence obtained from at least one randomised controlled trial.
IIa Evidence obtained from at least one well-designed controlled study without randomisation.
IIb Evidence obtained from at least one other type of well-designed quasi-experimental study.
III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies and case studies.
IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities.
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