MON-569 - Novel Use of AID for the Management of MODY in Pregnancy

Maturity Onset Diabetes of Young (MODY), a monogenic autosomal dominant form of diabetes accounts for 1-2% of all diabetes cases. MODY subtypes 1,2 and 3 account for 95% of cases. GCK-MODY (MODY2) in pregnancy is associated with mild fasting hyperglycemia, that typically requires no treatment outside of pregnancy. Management during pregnancy is determined by fetal genotype or evidence of macrosomia on serial ultrasound monitoring of fetal growth and abdominal circumference. Automated Insulin Delivery (AID) systems are the preferred treatment for type 1 diabetes. I present this case wherein, we successfully managed patient with MODY2 in pregnancy using AID.
A 25 year old woman presented to our clinic at 8 weeks GA for the management of diabetes in pregnancy. Her Hb A1c ranged between 6.1 and 6.6%. BMI was 23.1. She had been misdiagnosed with type 2 diabetes as a child. Her fasting blood sugars failed to respond to metformin or basal insulin. She reported strong family history of type 2 diabetes on maternal side of her family (mother, sister, maternal aunt, maternal grandmother). MODY2 was suspected following an extensive evaluation of hyperglycemia, which included negative results for type 1 diabetes antibody screening. She did not pursue genetic testing for MODY at that time. Patient was asked to monitor fasting blood glucose (FBG) and 2h post prandial blood glucose (PPBG) readings during her pregnancy. Due to the nature of her work as a nurse, for ease of monitoring glycemic trends, she started using CGM (dexcom G7) at 12 weeks gestational age. Serial fetal USG monitoring in her second trimester showed a trend towards macrosomia, fetal growth percentile increased from 26 to 75th percentile with simultaneous increase in fetal abdominal circumference. Her FBG ranges 100-120 mg/dl and 2h PPBG ranged 120-160 mg/dl at this time. We discussed treatment options, bolus insulin therapy versus AID. Patient opted to start on omnipod 5 with dexcom G7. Basal rate was 0.1 unit/h with I:C of 1:15, SF of 50. The higher fasting BG threshold of 110 mg/dl with AID worked well for this patient. Post prandial BG remained less than 120 mg/dl following initiation of insulin pump therapy. Her total weight gain during pregnancy was 27 lbs. Following premature rupture of membranes and spontaneous vaginal delivery, her baby was born at 36 weeks gestational age with birth weight of 5 lbs 8 ounces. Following delivery, insulin pump therapy was discontinued.
The patient completed genetic testing post-parum. She tested positive for GCK mutation, heterozygous for c.1142T>C (p.Met381Thr). Her child tested negative for GCK mutation, which confirmed our clinical suspicion based on serial ultrasound monitoring.

Conclusion: Use of AID offers unique opportunity for treating MODY2 in pregnancy, when the fetus is suspected to be unaffected.

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