Glycaemic targets during pregnancy for women with pre-existing diabetes

Glycaemic targets during pregnancy must be individualised, aiming to avoid hypoglycaemia. Pregnant women with type 1 diabetes are at higher risk of hypoglycaemia than those with type 2 diabetes, particularly during the first trimester. See Hypoglycaemia for further information.

Note: Individualise glycaemic targets in pregnant women with diabetes, aiming to avoid hypoglycaemia.
The optimal target blood glucose concentration in pregnancy is not clear1. For women with pre-existing diabetes using blood glucose concentration monitoring (eg capillary [finger-prick] checking), suggested targets during pregnancy are given in Suggested blood glucose concentration targets during pregnancy for women with pre-existing diabetes.
Table 1. Suggested blood glucose concentration targets during pregnancy for women with pre-existing diabetes

[NB1]

Timing of blood sample

Blood glucose concentration target

fasting and preprandial

4 to 5.3 mmol/L

1 hour postprandial

5.5 to 7.8 mmol/L

2 hours postprandial

5.0 to 6.7 mmol/L

Note:

NB1: These targets are a guide—targets may need to be individualised to avoid hypoglycaemia, particularly in women with type 1 diabetes.

For women with pre-existing type 1 diabetes using continuous glucose monitoring (CGM) or flash glucose monitoring, the suggested interstitial glucose concentration targets during pregnancy are given in Suggested interstitial glucose concentration targets during pregnancy for women with pre-existing type 1 diabetes. Interstitial glucose concentration targets for women with pre-existing type 2 diabetes are not defined because more data are needed.

Table 2. Suggested interstitial glucose concentration targets during pregnancy for women with pre-existing type 1 diabetes[NB1]

Parameter

Target

interstitial glucose concentration range

3.5 to 7.8 mmol/L

time in range

more than 70% of the day (16.8 hours per day)

time below range

less than 4% of the day (1 hour per day) at less than 3.5 mmol/L

less than 1% of the day (15 minutes per day) at less than 3.0 mmol/L

glycaemic variability (%CV)

36% or less

Note:

%CV = coefficient of variation

NB1: Continuous glucose monitoring (CGM) and flash glucose monitoring systems measure the glucose concentration in interstitial fluid. See Interstitial fluid glucose monitoring systems for information about CGM and flash glucose monitoring.

The normal glycated haemoglobin (HbA1c) in pregnant women without diabetes is less than 37 mmol/mol (5.5%); this is lower than in nonpregnant women because of haemodilution and more rapid red cell turnover during pregnancy. In women with diabetes, aim for the following HbA1c targets, while minimising the risk of hypoglycaemia:

  • 48 mmol/mol (6.5%) or less in the first trimester (up to 10 weeks’ gestation)
  • 42 mmol/mol (6%) or less in the second and third trimester (from 10 weeks’ gestation).
1 For further information, see McElduff A, Moses RG. Insulin therapy in pregnancy. Endocrinol Metab Clin North Am 2012;41(1):161-73. URLReturn