Intravenous insulin infusion

In the peripartum period, the insulin requirement for a woman with pre-existing diabetes is highly variable. This is best managed using an intravenous insulin infusion run concurrently with a glucose 5% intravenous infusion.

The initial intravenous insulin infusion rate should be based on the woman’s usual insulin requirements. It can be calculated by dividing the total daily insulin dose by 24 (eg for a total daily insulin dose of 48 units, the initial insulin infusion rate should be 2 units per hour).

Adjustment of intravenous insulin infusion rate should be based on hourly capillary (finger-prick) blood glucose concentrations. Always use local protocols (if available) and seek expert advice.

If a local protocol is not available, a suitable regimen for glycaemic management in women with type 1 diabetes during labour is:

short-acting insulin by intravenous infusion. Base initial infusion rate on usual insulin requirements (see above), then adjust infusion rate as outlined in Suggested adjustment of intravenous insulin infusion rate during labour (Table 18.25) (see Action profiles of insulin formulations for insulin formulations)

PLUS

glucose 5% 167 mL/hour (1 L every 6 hours) by intravenous infusion.

The intravenous insulin and glucose infusions should be run concurrently (in separate lines) and be given by a single cannula (piggyback) to ensure that if one infusion is stopped the other will also be stopped.

After delivery, continue monitoring blood glucose concentrations and adjust therapy as required (see Postpartum management of women with pre-existing diabetes).

Table 1. Suggested adjustment of intravenous insulin infusion rate during labour (Table 18.25)[NB1] [NB2] [NB3]
Printable table
BGC (mmol/L)	BGC trend	Usual total daily insulin dose
		100 units or less	more than 100 units
less than 4	regardless of trend	Suspend infusion [NB4] Increase glucose 5% infusion rate to 250 mL/hour Monitor BGC every 15 minutes until it is more than 5 mmol/L, then every hour NOTIFY THE TREATING DOCTOR
4 to 4.4	falling	Reduce infusion rate by 2 units/hour OR Suspend infusion if rate is 2 units/hour or less [NB4]	For total daily insulin dose 101 to 150 units: Reduce infusion rate by 3 units/hour OR Suspend infusion if rate is 3 units/hour or less [NB4] For total daily insulin dose more than 150 units: Reduce infusion rate by 4 units/hour OR Suspend infusion if rate is 4 units/hour or less [NB4]
	stable	Reduce infusion rate by 1 unit/hour OR Suspend infusion if rate is 1 unit/hour or less [NB4]	Reduce infusion rate by 2 units/hour OR Suspend infusion if rate is 2 units/hour or less [NB4]
	rising	No change
4.5 to 4.9	falling	Reduce infusion rate by 1 unit/hour OR Suspend infusion if rate is 1 unit/hour or less [NB4]	Reduce infusion rate by 2 units/hour OR Suspend infusion if rate is 2 units/hour or less [NB4]
	stable	No change
	rising
5 to 6.9	falling	Reduce infusion rate by 1 unit/hour OR For type 2 diabetes: Suspend infusion if rate is 1 unit/hour or less [NB4] For type 1 diabetes: Reduce infusion rate to 0.5 units/hour if rate is 1 unit/hour
	stable	No change
	rising
7 to 8.4	falling	No change
	stable	Increase infusion rate by 1 unit/hour
	rising	Increase infusion rate by 1 unit/hour	Increase infusion rate by 2 units/hour
8.5 to 10	falling	Increase infusion rate by 1 unit/hour	Increase infusion rate by 2 units/hour
	stable	Increase infusion rate by 2 units/hour	Increase infusion rate by 3 units/hour
	rising	Increase infusion rate by 3 units/hour NOTIFY THE TREATING DOCTOR
more than 10	regardless of trend	NOTIFY THE TREATING DOCTOR
Note: BGC = blood glucose concentration NB1: Base the adjustment of intravenous insulin infusion rate on hourly capillary (finger-prick) BGCs during labour and for at least 6 hours after delivery (see also Postpartum management of women with pre-existing diabetes). NB2: Titration may need to be more conservative or more aggressive depending on the initial infusion rate and the rate of change in the BGC. If the BGC target is not achieved, promptly notify the treating doctor. NB3: The intravenous insulin infusion must run concurrently with a glucose 5% intravenous infusion. Run infusions in separate lines but give by a single cannula (piggyback). NB4: Restart insulin infusion at a rate of 1 unit/hour when BGC is more than 6 mmol/L. For women with type 1 diabetes, do not suspend the insulin infusion for more than 1 hour.