Different Intensities of Glycaemic Control for Pregnant Women with Pre-Existing Diabetes

Summary

A Cochrane review [Abstract] 1 included 3 studies with a total of 233 subjects. In a trial of 60 women and babies comparing tight (≤ 5.6 mmol/L fasting blood glucose (FBG)); moderate (5.6 to 6.7); and loose (6.7 to 8.9) glycaemic control targets, there were 2 neonatal deaths in the loose and none in the tight or moderate groups. There were significantly fewer women with pre-eclampsia (RR 0.11, 95% CI 0.01 to 0.99), fewer caesareans (RR 0.28, 95% CI 0.10 to 0.78), and fewer birthweights greater than 90th centile (RR 0.01, 95% CI 0.00 to 0.20) in the combined tight-moderate compared with the loose group. Two trials compared very tight (3.33 to 5.0 mmol/L FBG) with tight-moderate (4.45 to 6.38) glycaemic control targets. In these two trials glycaemic control was not significantly different between the very tight and tight-moderate groups by the third trimester. No significant differences were seen.

A multicentre open-label RCT 2 included 325 women with type 1 diabetes and pregnant<14 weeks or planning pregnancy. Participants were randomly assigned to either continuous glucose monitoring (CGM) in addition to capillary glucose monitoring or capillary glucose monitoring alone. There was a small nonsignificant difference in HbA1c in pregnant women using CGM (mean difference -0.19%). Pregnant CGM users spent more time in target (68% vs 61%; p=0.0034) and less time hyperglycaemic (27% vs 32%; p=0.0279) than did pregnant control participants, with comparable severe hypoglycaemia episodes (18 CGM and 21 control) and time spent hypoglycaemic (3% vs 4%; p=0.10). Neonatal health outcomes were significantly improved, with lower incidence of large for gestational age (odds ratio 0.51, 95% CI 0.28 to 0.90; p=0.0210), fewer neonatal intensive care admissions lasting more than 24 h (0.48; 0.26 to 0.86; p=0.0157), fewer incidences of neonatal hypoglycaemia (0.45; 0.22 to 0.89; p=0.0250), and 1-day shorter length of hospital stay (p=0.0091).

A secondary analysis of the above mentioned trial 3 found that during the second and third trimesters, mothers of infants with neonatal hypoglycaemia had higher HbA1c [48 ± 7 (6.6 ± 0.6) vs. 45 ± 7 (6.2 ± 0.6); P = 0.0009 and 50 ± 7 (6.7 ± 0.6) vs. 46 ± 7 (6.3 ± 0.6); P = 0.0001] and lower continuous glucose monitoring time-in-range (46% vs. 53%; P = 0.004 and 60% vs. 66%; P = 0.03). Neonates with hypoglycaemia had higher birthweight> 97.7th centile (63% vs. 34%; P < 0.0001).