An inpatient has a different insulin sensitivity from at home: less food, more stress, often corticosteroids, often impaired renal function. Prescribe basal insulin, mealtime insulin and the correction dose as three separate entries on the drug chart.
Glucose targets on the ward
| Situation | Target plasma glucose |
|---|---|
| Most inpatients | 6–10 mmol/L |
| Frail older people, a short expected survival, a high risk of hypoglycaemia | 8–12 mmol/L |
| The critically ill patient in intensive care | According to the local protocol |
Avoid tight targets in inpatients. Hypoglycaemia on the ward is more dangerous than moderate hyperglycaemia over a few days.
Principles
| Insulin component | Function | Who needs it |
|---|---|---|
| Basal insulin (intermediate- or long-acting) | Covers fasting glucose production | Everyone with type 1 diabetes, always, including while fasting. Many with type 2 |
| Mealtime insulin (rapid-acting) | Covers the carbohydrate in the meal | Anyone who is eating |
| Correction dose (rapid-acting) | Corrects a currently high value | As required, in addition to the mealtime dose |
Never stop basal insulin in a person with type 1 diabetes, not even before fasting or an investigation. Stopping it leads to ketoacidosis within hours.
Treatment with correction doses alone according to the glucose value, without basal insulin (a so-called sliding scale), gives poorer control and is not recommended as the sole regimen.
Common situations
| Situation | Management |
|---|---|
| Fasting before an investigation, type 1 | Continue basal insulin, often at a somewhat reduced dose. Withhold mealtime insulin. Monitor the glucose closely |
| Fasting before an investigation, type 2 | Withhold metformin, SGLT2 inhibitors and sulfonylureas. Basal insulin often reduced |
| Corticosteroid treatment | This causes marked hyperglycaemia above all in the afternoon and evening. Increase the mealtime insulin at lunch and dinner in the first instance. Measure the glucose before every meal and at bedtime |
| Enteral or parenteral nutrition | Insulin is needed around the clock. A continuous infusion or repeated doses, according to the local protocol |
| Renal failure | The insulin requirement falls. Reduce the dose and measure more frequently |
| Acute illness and infection | The insulin requirement rises, often despite a reduced food intake |
| Insulin pump | The patient manages the pump themselves where possible. In impaired consciousness or DKA: remove the pump and change to an infusion or injections |
Drugs for type 2 diabetes in inpatients
| Agent | The acutely ill inpatient |
|---|---|
| Metformin | Stop in acute kidney injury, hypoxia, shock, before contrast studies and before surgery. A risk of lactic acidosis |
| SGLT2 inhibitor | Stop in acute illness, fasting and surgery. A risk of euglycaemic ketoacidosis |
| Sulfonylurea | A high risk of hypoglycaemia in a patient who is eating poorly. Consider stopping it |
| GLP-1 receptor agonist | It can cause nausea and delayed gastric emptying. Bear this in mind before sedation and endoscopy |
| DPP-4 inhibitor | A low risk of hypoglycaemia; it can usually be continued |
Red flags and pitfalls
- Stopping basal insulin in type 1 diabetes. The single most dangerous prescribing decision on a ward.
- Not prescribing glucose measurement. Prescribe the measurement times at the same time as the insulin.
- Giving mealtime insulin to a patient who is not eating. Give it after the meal when the food intake is uncertain.
- Not writing the prescription for hypoglycaemia. See the separate quick reference.
- Forgetting to review the dose as the corticosteroid is tapered. The dose must come down in parallel, otherwise hypoglycaemia will follow.
- Discharge without a plan. Document what has been changed, who is following it up and when.
Sources
- American Diabetes Association, Standards of Care in Diabetes: diabetes care in the hospital.
- Endocrine Society clinical practice guideline on the management of hyperglycaemia in hospitalised adults.
- The summary of product characteristics for each insulin preparation.
