Background
Gestational Diabetes mellitus (GDM) is defined as pregnancy induced blood glucose intolerance or previously undiagnosed diabetes during pregnancy (1). RANZCOG and ADIPs advise screening for GDM at 24-28 weeks' gestation, preferably with OGTT or HbA1c level (1,2). Glucocorticoid usage is deemed as a risk factor for GDM and merits early pregnancy testing. We present two cases of pregnant individuals on long term prednisolone where early GDM screening was not performed.
Case A
Ms A, 36-year-old female, G1PO was diagnosed with polymorphic eruption of pregnancy (PUPP) at 25 weeks’ gestation and commenced on a five-day course of prednisolone. She had a further flare, so prednisolone dose was increased to 37.5mg. At 29 weeks’ gestation, she had a normal OGTT but was appropriately instructed to monitor BGLs at home. Post-prandial BGL was 9.9 mmol/L so 2 units of insulin aspart with meals was commenced and later increased to 5-7 units. She failed to attend her final appointment due to had premature rupture of membranes and was admitted to a tertiary hospital.
Case B
Ms B, 37-year-old female, G3 P1 with a background of known Ulcerative colitis (UC) was on long-term prednisolone therapy. She was seen during a planned appointment in Inflammatory Bowel clinic at 30 weeks’ gestation and found to have prematurely weaned her prednisone thus was re-established on 37.5mg. She did not undertake standard GDM screening via OGTT due to concerns of false positives but was instead instructed to check BGLs regularly. 3 post lunch levels were elevated and otherwise remained euglycaemic, hence did not require insulin.
Discussion
Research around the usage of glucocorticoids antenatally remains limited - some groups have investigated the use of high-dose, short term steroid therapy (i.e. <5 days) but none that report on the effects of longer-term glucocorticoid usage during the antenatal period (3,4). Concerns exist of misdiagnosing steroid induced hyperglycaemia as GDM – however, the effects of hyperglycaemia are still detrimental to mother and offspring, highlighting the need for specialist monitoring and management of any hyperglycaemia in pregnancy, regardless of cause. (5,6,7)
Conclusion
Recommendations around screening of GDM exist but are not always adhered to. For pregnant individuals on long term glucocorticoids, uncaptured events of SIHG or concerns of false positives, may result in untreated hyperglycaemia in pregnancy. Thus, in addition to early screening as per guidelines we suggest the consideration of BGL monitoring even in the setting of a negative OGTT.