Oral Presentation Society of Obstetric Medicine of Australia and New Zealand and Australasian Diabetes in Pregnancy Society Joint Scientific Meeting 2017

Using insulin pumps in pregnancy: understanding insulin pumps (#51)

Lynelle Boisseau 1
  1. ACT HEALTH, FADDEN, ACT, Australia

Management of type 1 diabetes necessitates the delivery of exogenous insulin to replace absent endogenous secretion. The delivery needs to mimic as closely as possible the normal physiological pattern of insulin secretion, which includes basal insulin release and meal-related secretion spikes. This is achieved through either Multiple Daily Injections (MDI) of basal and rapid acting insulins or Continuous Subcutanenous Insulin Infusion (CSII) of rapid acting insulin via insulin pump.

An insulin pump is an external battery powered mechanical device about the size of a mobile phone. Rapid acting insulin (insulin aspart (Novorapid) or insulin lispro (Humalog)) within a reservoir is pumped via thin tubing to a small cannula inserted subcutaneously controlled by a computer according to settings.

Pump settings include:

  • Basal infusion rates: custom built rates variable according to the time of day.
  • Bolus settings: carbohydrate(CHO) to insulin ratio (CHO:insulin), as grams of CHO/unit of insulin; insulin sensitivity factor (ISF), as mmol/L glucose lowering per unit of insulin.
  • Glucose target (e.g. 5.5±5 mmol/L)
  • The CHO:Insulin ratio, ISF and glucose targets can vary according to the time of the day.

All settings are revised periodically according to glucose profiles. Lower or higher temporary basal rates can be set for exercise/ sick days. Bolus insulin is given at times of meals and snacks according to carbohydrate content and the blood glucose concentration. Boluses can also be given as corrections for elevated blood glucose levels between meals.

Insulin pumps can have connectivity with continuous glucose monitoring (CGM) with a low glucose suspend feature.

As insulin pumps infuse rapid insulin only, their failure will rapidly result in hypoinsulinaemia, with a high risk of diabetic ketoacidosis.

Insulin pumps offer increased flexibility in insulin delivery and should assist women with type 1 diabetes to achieve optimal glycaemic control for improved pregnancy outcomes.