HbA1c for Diagnosis (including pregnancy and in children). Aidan McElduff The Discipline of Medicine, The University of Sydney

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1 HbA1c for Diagnosis (including pregnancy and in children). Aidan McElduff The Discipline of Medicine, The University of Sydney

2 DECLARATION OF INTEREST/DISCLOSURES Nil I acknowledge and thank Prof David McIntyre who provided me with several of these slides

3 Definitions HbA1c is directly proportional to the total amount of glucose in the circulation over the lifespan of the RBCs The Past GTT measures your glucose response to 75g of glucose with reflects your glucose response to your diet The Present/Future

4 The GTT for diagnosis Only uniform after 1979 Revise in 2003 HbA1c accepted 2011

5 Background Diabetes, a multitude of diseases characterised by hyperglycaemia and associated with specific complications Threshold for diagnosis defined by risk of retinopathy May be asymptomatic The goal of (HbA1c) screening is to detect the asymptomatic person at long term risk

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7 HbA1c: PREGNANCY? The goal of (HbA1c) screening is to detect the risk of adverse pregnancy outcomes for both the mother and the fetus/neonate due to diabetes including diabetes mellitus in pregnancy (WHO)? lesser degrees of hyperglycaemia ie a GDM equivalent

8 HbA1c: PREGNANCY? 2 issues Early v Late Mild (GDM) v Severe (Diabetes)

9 Relation between first-trimester A1C level and pregnancy outcome Pre existing diabetes 376 pregnancies with good outcomes and 98 with adverse outcomes Gunnar L. Nielsen et al. Diab Care 2006;29: by American Diabetes Association

10 Late pregnancy Diabetes Care. 2012;35:574-80

11 Late pregnancy Diabetes Care. 2012;35:574-80

12 Late pregnancy Adjusting glucose for HbA1c and HbA1c for glucose Diabetes Care. 2012;35:574-80

13 HbA1c in late pregnancy In late pregnancy, for minor degrees of hyperglycaemia (gestational diabetes), glycated haemoglobin has been shown to be less effective in predicting adverse pregnancy outcomes than the traditional 75 g PGTT (Diabetes Care. 2012, 35:574).

14 HbA1c: PREGNANCY? Potential use in early pregnancy to detect T2DM important IFG / IGT possibly important (not GDM as defined by GTT)

15 HbA1c in early pregnancy Epidemiology Balaji V et al Diab Care 2007 Hughes R Diab Care 2014 Fong A AJOG 2015 Treatment Rowan J ANZJOG 2014 Osmundsen S AJOG 2015 (in press)

16 Epidemiology - HbA1c early pregnancy Balaji n=225 in first trimester HbA1c 6.0 % identified all cases of first trimester GDM Hughes n=16,122 in first trimester HbA1c 5.9 % identified all (Overt) diabetes in pregnancy and 64% had GDM HbA1c 5.9% associated with: 2 x risk of congenital anomalies / PET / S. dystocia 3 x risk of perinatal death

17 Epidemiology - HbA1c early pregnancy Fong n = 55 with HbA1c % in first trimester GDM in 27%. Early Rx in 3 women Variable use of 1 step and 2 step GDM diagnosis Adjusted OR for GDM 2.38 ( )

18 Therapy? - HbA1c early pregnancy Rowan n = 80 HbA1c 5.9 % but N OGTT (NZ) Seen regularly in clinic. 78% required insulin or metformin, 64% had abnormal post partum HbA1c 5.9 % Osmundsen n=82, HbA1c in first trimester RCT early Rx vs. no treatment Early Rx less GDM in lean women only, lower HbA1c throughout pregnancy, earlier insulin use, no difference in other outcomes

19 Conclusions; Pregnancy HbA1c in early pregnancy Simple, practical, non fasting test Identifies women with pre existing DM and pre diabetes worthy of treatment Identifies women at risk of adverse pregnancy outcomes Some caveats (e.g. abnormal Hb, anemia,?ethnic variability) Definitely better than nothing Potential thresholds %

20 HbA1c: Children There are almost no published data on this issue in children. In NSW, type 2 diabetes is about 10% of diabetes in adolescence. Type 2 diabetes is rare before puberty. Most diabetes in children is diagnosed clinically on symptoms and an appropriately elevated plasma glucose level.

21 HbA1c: Children The international paediatric guidelines suggests that glycated haemoglobin may be useful as a diagnostic aid in borderline situations or in incidentally discovered mild hyperglycaemia in an asymptomatic child. The test is not recommended for routine use Pediatric Diabetes 2014: 15(Suppl. 20): 4 17