Glucose lows, placental flow: hypoglycaemia as a harbinger of placental insufficiency — ASN Events
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Glucose lows, placental flow: hypoglycaemia as a harbinger of placental insufficiency (#430)

Chih Ying (Maggie) Ko 1 2 , Ning Zhang 1 2 , Sarah Abdo 1 3 , Tang Wong 1 2 3
  1. Diabetes and Endocrinology, Bankstown Lidcombe Hospital, Bankstown, NSW, Australia
  2. School of Clinical Medicine, Faculty of Medicine and Health , UNSW, Sydney, NSW, Australia
  3. School of Medicine, Western Sydney University, Sydney, NSW, Australia

Overt diabetes in pregnancy is characterised by hyperglycaemia and increasing insulin requirements; the emergence of hypoglycaemia with falling insulin needs in late pregnancy is unexpected and may signal placental insufficiency. We describe a case in which recurrent hypoglycaemia preceded evidence of placental dysfunction.

A 40-year-old woman was referred at 29 weeks’ gestation with overt diabetes in pregnancy and was commenced on insulin. By 34 weeks’ gestation, she was experiencing frequent, unexplained hypoglycaemic episodes, requiring down-titration of insulin, with total daily dose (TDD) of insulin reduced from 66 units at 31+2 weeks’ gestation to 53 units at 35+2 weeks’ gestation (approximating 20% reduction). She was referred to the birthing unit for assessment given this unexpected reduction in insulin requirements.  

Ultrasonography findings were reassuring with normal umbilical artery doppler and normal liquor volume, and CTG showed heart rate 140bpm with no deceleration. However her BP was 130/70mmHg, sFLT/PIGF ratio 42 (normal < 38), with worsening renal function (serum creatinine 105 mmol compared to 75 mmol at baseline) and platelet count 104 x 109/L. Her insulin requirements further reduced to TDD of 30 units at 35+4 weeks gestation from 66 units at 31+2 weeks’ gestation, representing, now, a 45% reduction. In the setting of significant reduction in insulin requirements, uptrending BP, elevated sFLT/PIGF ratio, rising creatinine and thrombocytopaenia indicating likely evolving placental insufficiency, the decision was made for delivery at 35+5 weeks’ gestation.

A live female infant was born at 35+6 weeks gestation. Placental histology showed peri-villous fibrin deposition, consistent with placental insufficiency. 

There is data supporting the usage of falling insulin requirements (FIR), especially ≥15%, as a marker of impending placental insufficiency. FIR has been associated with higher sFLT/PIGF ratios, pre-eclampsia, foetal growth restriction, neonatal intensive care admission, and prematurity. However, FIR remains an under-recognised clinical marker, with significant variation in management.