Poor glycaemic control is common amongst inpatients due to the stress response that occurs during illness. The best way to optimize glucose control is by using insulin in a regimen that imitates the physiological insulin profile, i.e. a basal bolus insulin regimen. This can be started temporarily in patients who do not normally take insulin or changed from other insulin regimens.
When insulin is commenced, re-prescribe it every day so that doses are not missed. By reviewing today’s glucose levels, predict and prescribe tomorrow’s insulin doses.
Understanding the action profiles of the basal and bolus insulins will help you to make the most of the insulin regimen you prescribe.
Bolus or rapid-acting insulin analogues:
When to start insulin
In hospital, commence insulin in all patients whose glucose levels are persistently >12 mmol/L.
This includes patients with:
How to start insulin
Use a basal bolus insulin regimen for all inpatients.
1. For the basal insulin
2. For the bolus insulin
Supplemental doses of Bolus Insulin
The meal time dose of rapid-acting insulin can be supplemented if glucose levels are high. This is called a “supplemental dose” and aims to lower and stabilize glucose levels. It is optional and may be useful when the glucose levels are high now, but expected to improve as the illness resolves eg. sepsis.
You can calculate the supplemental doses based on your patient’s weight (which predicts their response to insulin). Be aware that these supplemental insulin doses can increase the risk of daytime hypoglycaemia.
How to adjust insulin doses
When your patient is on a basal bolus insulin regimen, the doses may need to be adjusted every day to manage out-of-range glucose levels.
If the daytime glucose levels are all above 12 mmol/L, increase the basal and bolus doses the next day. Prescribe insulin for tomorrow based on today’s pattern of hyperglycaemia. This ensures your patient receives all their insulin doses without any missed doses
When glucose levels are 5 – 10 mmol/L, continue these doses but ensure they are re-prescribed every day to ensure no doses are missed in your absence.
Supplemental doses of Bolus Insulin
Bolus doses at meal times can be supplemented if glucose levels are high before meals. This is called a “supplemental dose” of rapid-acting insulin. This is optional, and the following suggested doses are based on the weight of your patient (which predicts their response to insulin). Be aware that these supplemental insulin doses can increase the risk of daytime hypoglycaemia.
Sliding scale insulin: why it is not recommended
Sliding scale insulin is when rapid-acting insulin is prescribed on its own without basal insulin to match. The dose is usually given at meal times and matched to high glucose levels only. Where these insulins last up to 3 hours, their effect wears off, and the glucose levels rise again.
Sliding scales do not match the physiological insulin profile and do not serve your patient well. It does not treat hyperglycemia adequately and is a waste of effort.
How to change premixed insulin to basal bolus insulin regimen
A basal bolus insulin regimen is the best way to control diabetes in hospital when glucose levels are poorly controlled and your patient is eating erratically eg. vomiting or fasting. If your patient prefers their usual regimen, aim to resume this at the time of discharge.
To change from the pre-mixed insulin regimen, calculate the total daily dose (TDD):
How to add bolus insulin doses to daily Lantus or Toujeo
If your patient takes once or twice daily Lantus or Toujeo, and the daytime glucose levels are >12 mmol/L, add bolus insulin doses for meals ie. translate the insulin to a basal bolus insulin regimen. This is more effective than increasing the dose of Lantus or Toujeo.
Bolus insulin dose = Lantus or Toujeo dose ÷ 3