Oral Presentation Australasian Diabetes in Pregnancy Society Annual Scientific Meeting 2016

Changes in insulin requirement and glycaemic control during the third trimester in women with type 1 diabetes on insulin pump therapy. (#6)

Michele Bardin 1 , Alexis Shub 2 , Deborah Boyce 2 , Catharine McNamara 2 , Lucy McBride 2 , Jas-mine Seah 1 , Elif I. Ekinci 1 , Christine Houlihan 1 2
  1. Depts. Endocrinology and Medicine, Austin Health, University of Melbourne, Melbourne, VIC, Australia
  2. Mercy Hospital for Women, Melbourne, VIC, Australia

Background:

Increase in insulin requirements across gestation occurs in maternal Type 1 diabetes (T1DM), predominantly secondary to increased bolus insulin(1). However, towards end of gestation, some women on multiple daily injections have a fall in insulin requirements potentially related to altered placental function or foetal draw(2).

Aim:

To examine changes in insulin requirements in maternal T1DM patients on Insulin Pump Therapy.

Methods:

We analysed data in pregnant women with T1DM who received antenatal care at Mercy Health, 2010-2016.  Weekly averages of total, basal, and bolus insulin, carbohydrate intake, blood glucose (BGLs), and episodes of BGL <3.9mmol/L were recorded in the 1st(T1), 2nd and the 3rd(T3) trimester at 29,31,33,35,36,37 weeks. T3 time-points were classified as week(s) prior (1, 2-3, 5 and 7 weeks) to delivery to account for variable gestations. Differences were analysed by repeated measures ANOVA.

Results:

Seventeen patients’ pump data have been analysed. Gestation at delivery: 36.7±1.3 weeks, booking BMI 24.2±8kg/m2. There was increased total insulin between 7 and 5 weeks pre-delivery (55.05±14.86 vs 62.26±17.1 units; p=0.01), no change thereafter. Carbohydrate intake remained constant with no difference in basal insulin (35.43±18.3 vs 31.9±19.5units;p=0.11) and bolus insulin (38.8±18.6 vs 33.1±18.9units p=0.19); weeks 1 vs 7. Reduced average BGL occurred before delivery (7.4±1.2mmol/L vs 8.4±1.7; p=0.03; weeks 1 vs 5). The percentage of BGL <3.9mmol/L was greater towards the end of gestation (9.2% vs 4.8%; p=0.036; week 1 vs 5). 10 of 17 patients showed some degree of decline in total insulin in the final gestational week (66.77±18.52 vs 63.01±17.94 units;p=0.003;weeks2 or 3 vs 1) translating to an average 6% insulin reduction (0.7 –14.3%).

Conclusion:

T3 is a dynamic time of change of insulin requirements and glycaemic control, seemingly unrelated to change in carbohydrate intake. Better characterisation of these parameters could assist in the management of maternal T1DM.

  1. Roeder HA, Moore TR, Ramos GA. Insulin pump dosing across gestation in women with well-controlled type 1 diabetes mellitus. Am J Obstet Gynecol. 2012 Oct;207(4):324. e1-5.
  2. A. Achong, L Callaway , M d'Emden. Insulin requirements in late pregnancy in women with type 1 diabetes mellitis: A retrospective review. Diabetes Research and Clinical Practice 2012: 98 ; 414-421.