- Clinical science
Insulin is an anabolic peptide hormone that is produced and secreted from beta cells located in the islets of Langerhans of the pancreas. It has important metabolic functions, which include promoting the storage of carbohydrates, amino acids, and fat in the liver, skeletal muscle, and adipose tissues. By modulating glucose absorption from the blood, insulin lowers blood glucose levels. Insulin therapy is an important part of treatment for individuals with insufficient or absent insulin production (e.g., diabetes mellitus, gestational diabetes). Several insulin analogs (e.g., insulin glargine) are available that are related to human insulin but have a different molecular structure and differ in onset, peak, and duration compared to human insulin. It is crucial that patients receiving insulin therapy undergo in-depth training to prevent potentially life-threatening conditions such as hypoglycemia as a result of an insulin overdose or drug interactions.
For further information, see also inpatient management of hyperglycemia.and
|Overview of the different types of insulin|
|Types of insulin||Pharmacokinetics ||Application ||Additional considerations |
|Insulin lispro|| || || |
|Regular insulin|| || |
|NPH insulin|| || |
|Insulin glargine|| || || |
|Mixed insulin|| |
Rapid acting insulins leave no LAG - to remember Lispro, Aspart, Glulisine
- Insulin is an anabolic peptide hormone; that is produced and secreted from beta cells in the islets of Langerhans of the pancreas in response to a rise in blood glucose
- Several insulin analogs (e.g., insulin glargine) are available that are related to human insulin but have a different molecular structure; after injection they exert the same actions but differ in onset, peak and duration compared to human insulin
- Insulin binds to insulin receptors (a type of tyrosine kinase receptor) located in various tissues in the body (e.g., liver, skeletal muscle, adipose tissue) and has the following actions:
|Lipid metabolism|| |
|Protein metabolism|| |
|Other effects|| |
- Type 1 diabetes mellitus
- Type 2 diabetes mellitus, if weight normalization, physical activity, and oral antidiabetic drugs do not keep blood glucose levels in the target range
- Pancreatic insufficiency with secondary diabetes
- Gestational diabetes, if change of diet is not sufficient
- Acute hyperkalemia: A drip containing regular insulin and a solution of glucose reduces blood potassium levels.
- See also “ ” in .
Basal-bolus insulin regimen 
- Calculate the total daily dose of insulin (TDD) needed.
- If the patient is already on a correction scale: Increase or decrease total daily dose by 10–20% as needed.
- If the patient is lean, has T1DM, age ≥ 70 years, and/or GFR < 60 mL/min: 0.2–0.3 units/kg
- If none of the above criteria applies, use the blood glucose level:
- BG 140–200 mg/dL: 0.4 units/kg
- BG > 200 mg/dL: 0.5 units/kg
- Divide the total daily dose of insulin into basal insulin (50%) and nutritional insulin (50%).
- Add sliding scale insulin as supplemental insulin.
- Take 5% of the TDD (e.g., 50 → 2.5).
- Round down to the safest whole number (e.g., 2.5 → 2).
- For every 40 mg/dL (2.2 mmol/L) above the goal serum glucose of 140 mg/dL, increase the nutritional insulin scale by this increment.
- Adjust as needed.
Decrease or hold nutritional insulin if the patient is NPO.
- If the patient is eating all or most of each meal: administer as short-acting insulin (or rapid-acting insulin) before each meal and at bedtime
- If the patient is not eating: administer as short-acting insulin every 6 hours
|Blood glucose (mg/dL)||Insulin units|
|Insulin sensitive||Usual insulin||Insulin resistant|
If the blood glucose is < 70 mg/dL, hold all insulin and administer hypoglycemia measures.
- Convert glucocorticoid to equivalent prednisone dose (see ).
- Calculate daily NPH dose based on prednisone dose equivalent and patient weight.
- Administer glucocorticoid with NPH as a single dose in the morning.
|Prednisone dose equivalent (mg/day)||NPH (units/kg/day)|
NPH doses should be administered in addition to usual basal insulin in patients who are already receiving insulin.
Enteral nutrition 
- Determine basal insulin needs.
- For patients already on insulin: Continue prior dose or administer 30–50% of the total daily dose as long-acting insulin (e.g., glargine) daily.
- For patients not already on insulin, consider:
- 5 units of NPH every 12 hours
- or 10 units of glargine (or equivalent) daily
- Add nutritional insulin
- For patients receiving continuous tube feedings
- For patients receiving bolus feeding
- Add sliding scale insulin as supplemental insulin.
- Adjust as needed to glycemic targets, changes in medication, and changes in nutrition.
Patients with type 1 diabetes mellitus require basal insulin even if (enteral) feeding is discontinued.
Total parenteral nutrition (TPN) 
- Add short-acting insulin to IV parenteral nutrition solution.
- Diabetic patient: 1 unit per 10–15 g dextrose
- Nondiabetic patient: 0.5 units per 10 g dextrose
- Add sliding scale insulin as supplemental insulin: Administer as short-acting insulin (e.g., regular insulin) every 6 hours or rapid-acting insulin (e.g., lispro) every 4 hours.
- Adapt protocol to glycemic targets, changes in medication, and changes in nutrition.