First trimester
At booking in women with NICE/ SIGN risk factors (BOX 1) perform HbA1c + random glucose. All women with risk factors given access to online resources on healthy eating in pregnancy with advice that routine screening may not be available eg
https://www.nhsinform.scot/ready-steady-baby/pregnancy/looking-after-yourself-and-your-baby/eating-well-in-pregnancy
Box 1. Risk factors
Previous GDM
- BMI >= 35 kg/m2 at booking
- Previous pancreatitis
- First degree relative with diabetes (sibling , parent, child NOT grandparent)
- Previous macrosomic baby weighing 4.5kg or above
- Family origin with high prevalence of diabetes (South Asian/black Caribbean/Middle eastern)
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Box 2. Interpretation at booking
If HbA1c ³ 48mmol/mol or random glucose ³11.1 mmol/l then treat as pre-existing diabetes
If HbA1c 41-47 or random glucose 9-11 mmol/ then treat as GDM, refer to diabetes teams
All others, random glucose and HbA1c at 26-28 weeks
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Later pregnancy
26-28 weeks
All women with risk factors (Box 1) have random glucose and HbA1c (Box 3).
Box 3 Interpretation of HbA1c /RBG third trimester
If HbA1c ³ 48 then treat as diabetes
If HbA1c 39-47 then treat as GDM
If random glucose ³ 9.0 mmol/l then treat as GDM
Note HbA1c lower in later pregnancy hence lower cut off
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At any point in pregnancy if clinical concern (Box 4) then random glucose and HbA1c (interpret as Box 3 )
Box 4
Baby with AC / EFW >95th centile
Polyhydramnios
Fasting glycosuria (>=2+)
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After pregnancy. for women felt to be at high risk of diabetes immediately after pregnancy (small minority) follow up will be arranged by diabetes teams. For majority HbA1c at 6 months is suggested .