Table 3.

Concordance between criteria in the diagnosis of gestational diabetes mellitus (GDM)

*A – Case-control study: 1999 WHO versus 2015 NICE*
1999 WHO∗	2015 NICE∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	233 (44.6)	30	1.7%
Normal	GDM	Yes	42 (8.1)	36	16.7%
GDM	Normal	Yes	0	-	-
GDM	GDM	No	247 (47.3)	37	22.1%
*B – Case-control study: 1999 WHO versus 2013 WHO*
1999 WHO∗	2013 WHO∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	213 (40.7)	31	1.4%
Normal	GDM	Yes	62 (11.9)	36	12.9%
GDM	Normal	Yes	50 (9.5)	34	8.2%
GDM	GDM	No	198 (37.9)	38	26.2%
*C – Case-control study: 2015 NICE versus 2013 WHO*
2015 NICE∗	2013 WHO∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	213 (40.8)	30	1.4%
Normal	GDM	Yes	20 (3.8)	33	5.0%
GDM	Normal	Yes	50 (9.6)	36	8.2%
GDM	GDM	No	239 (45.8)	37	24.1%
*D – Cohort study: 1999 WHO versus 2015 NICE*
1999 WHO∗	2015 NICE∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	6138 (88.6)	34	2.5%
Normal	GDM	Yes	119 (1.7)	37	17.7%
GDM	Normal	Yes	0	-	-
GDM	GDM	No	673 (9.7)	38	22.6%
*E – Cohort study: 1999 WHO versus 2013 WHO*
1999 WHO∗	2013 WHO∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	5,780 (83.4)	33	2.0%
Normal	GDM	Yes	477 (6.9)	37	13.2%
GDM	Normal	Yes	203 (2.9)	35	7.4%
GDM	GDM	No	470 (6.8)	38	29.2%
*F – Cohort study: 2015 NICE versus 2013 WHO*
2015 NICE∗	2013 WHO∗	Discordant?	n(%)	Median HbA1c, mmol/mol	Proportion with HbA1c≥42 mmol/mol
Normal	Normal	No	5,780 (83.4)	34	2.0%
Normal	GDM	Yes	358 (5.2)	37	11.7%
GDM	Normal	Yes	203 (2.9)	35	7.4%
GDM	GDM	No	589 (8.5)	39	26.8%

↵*Normal is defined as subgroup 1, while GDM is defined as subgroups 2–4 using the categorisation defined in the methods
HbA1c = glycated haemoglobin; NICE = National Institute for Health and Care Excellence; WHO = World Health Organization