Background:
Current ADIPS GDM Diagnostic Criteria are based on the risk of adverse outcomes that exceeds the estimated LGA risk from the HAPO Study by 1.75 times. Consideration is being given to changing criteria that exceed that estimated risk by 2.0 times.
Aim:
To examine the implications of this change in our patient cohort.
Methods:
From our Pregnancy Database, we examined de-identified prospectively collected demographic and outcome data from singleton GDM pregnancies (Mar2016-Mar2024). We compared cases diagnosed ≥24weeks gestation not meeting 2.0 OGTT diagnostic criterion [FBGL<5.3 and 1hrBGL<10.6 and 2hrBGL<9.0] (NoLongerGDM), with those who would be diagnosed [FBGL≥5.3 or 1hrBGL≥10.6 or 2hrBGL≥9.0] (NewCriteriaGDMOR2.0). All women were given appropriate education, undertook SMBG QID and were treated with insulin if treatment targets were not met – FBGL<5.3mmol/L, 1hrBGL<7.4, 2hrBGL<7.0. Metformin was not used. We compared differences in demographic and outcome findings between the groups. Outcomes assessed included insulin use, caesarean section, early delivery (<37weeks), LGA (>90th percentile), SGA (<10th percentile), neonatal hypoglycaemia (<2.6mmol/L) and neonatal jaundice (requiring phototherapy). For these analyses, we excluded ‘NoLongerGDM’ women diagnosed <24 weeks (N=331) as some/many of them may be diagnosed at 24-28 weeks if not meeting new criteria diagnosis early.
Results:
There were 2623 women with complete data: (1884 NewCriteriaGDM and 739 NoLongerGDM). NoLongerGDM women had lower maternal age, gravida/parity, BMI, glycaemic parameters, later GDM diagnosis and were less likely of South Asian and more likely European ethnicity. Characteristics/Outcomes are shown in the Table.
Within the ‘NoLongerGDM’ women, insulin treatment was associated with increasing maternal age (31.2±5.3 vs 30.1±5.2 years, p<0.01), higher maternal BMI (27.6±6.2 vs 25.7±5.6, p<0.0001), earlier GDM diagnosis (26.9±1.9 vs 27.4±2.4 weeks, p<0.001), higher HbA1c (5.2±0.4 vs 5.1±0.3%, p<0.0001) and higher proportion of South Asian (20.2 vs 12.8%, p<0.01) and Middle Eastern (31.0 vs 23.0%, p<0.05) ethnicities compared to non-insulin requiring women.
|
|
NewCriteriaGDMmean±SD or n(%) total=1884 |
NoLongerGDMmean±SD or n(%) total=739 |
p-Value |
|
Maternal |
|
|
|
|
Maternal Age (years) |
31.7±5.2 |
30.4±5.3 |
<0.0001 |
|
Gravida |
3.0±1.9 |
2.7±1.6 |
<0.001 |
|
Parity |
1.4±1.4 |
1.2±1.2 |
<0.001 |
|
Maternal BMI (kg/m2) |
27.1±6.0 |
26.3±5.9 |
<0.01 |
|
Total GWG (kg) |
11.7±6.5 |
12.7±6.3 |
<0.01 |
|
Gestational Age at diagnosis (weeks) |
23.3±5.9 |
27.2±2.2 |
<0.0001 |
|
East/Southeast Asian ethnicity |
464(24.6) |
169(22.9) |
NS |
|
South Asian ethnicity |
417 (22.1) |
113 (15.3) |
<0.0001 |
|
Middle Eastern ethnicity |
450 (23.9) |
190 (25.7) |
NS |
|
European ethnicity |
418 (22.2) |
213 (28.8) |
<0.001 |
|
OGTT fasting (mmol/L) |
5.2±1.4 |
4.8±0.4 |
<0.0001 |
|
OGTT 1-hour (mmol/L) |
10.3±2.0 |
9.0±1.4 |
<0.0001 |
|
OGTT 2-hour (mmol/L) |
8.3±2.0 |
7.2±1.3 |
<0.0001 |
|
HbA1c (%) |
5.2±0.4 |
5.1±0.4 |
<0.0001 |
|
Outcomes |
|
|
|
|
Insulin Use |
957 (50.8) |
348 (33.6) |
<0.0001 |
|
Maximum Total Insulin Dose |
31.1±29.8 |
19.1±14.3 |
<0.0001 |
|
Caesarean Section |
698 (37.0) |
243 (32.9) |
<0.05 |
|
Early Delivery |
125 (6.6) |
36 (4.9) |
NS |
|
LGA |
243 (12.9) |
67 (9.1) |
<0.01 |
|
SGA |
143 (7.6) |
64 (8.7) |
NS |
|
Neonatal Hypoglycaemia |
209 (11.1) |
64 (8.7) |
NS |
|
Neonatal Jaundice |
107 (5.7) |
39 (5.3) |
NS |
|
GWG: Gestational Weight Gain, OGTT: Oral Glucose Tolerance Test, LGA: Large for Gestational Age, SGA: Small for Gestational Age |
Conclusions:
In this patient cohort, implementation of New 2.0 GDM Diagnostic Criteria would result in at least 28% fewer diagnoses. “NoLongerGDM” women had lower rates of LGA and caesarean section, but one third did require insulin treatment. These women, particularly those with higher maternal age, BMI, HbA1c and those of South Asian and Middle Eastern ethnicities, may still need close observation for adverse pregnancy outcomes and/or models of care reflecting their intermediate risk stratum (between OR1.75 and OR2.0 women).