- Clinical science
- Physician
Insulin
Summary
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 on insulin therapy and regimens, see insulin therapy.
Overview
Types of insulin | Effect | Application | Special features |
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Rapid-acting insulin | |||
Insulin lispro |
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Insulin aspart | |||
Insulin glulisine | |||
Short-acting insulin | |||
Regular insulin |
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Intermediate-acting insulin | |||
NPH insulin |
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Long-acting insulin | |||
Insulin glargine |
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Insulin detemir | |||
Insulin degludec | |||
Ultralente insulin | |||
Mixed insulin | |||
Mixed insulin |
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Effects
- 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:
Increases | Decreases | |
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Carbohydrate metabolism |
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Lipid metabolism |
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Protein metabolism |
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Other effects |
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References:[1][2]
Side effects
- Hypoglycemia
- Weight gain
- Lipodystrophy at the injection site
- Pain and erythema at injection site
- Hypokalemia
- Allergic reactions (rare)
- Edema (rare)
We list the most important adverse effects. The selection is not exhaustive.
Indications
- Type 1 diabetes mellitus
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Type 2 diabetes mellitus, if weight normalization, physical activity, and oral antidiabetic drugs do not keep blood glucose levels in the target range
- All type 2 diabetic patients with end stage renal failure (oral antidiabetic drugs are contraindicated in this case)
- 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 “insulin therapy” in diabetes mellitus.
Insulin regimens
Basal-bolus insulin regimen [3][4]
- 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%).
- Basal insulin: Administer as long-acting insulin (e.g., glargine) at bedtime.
- Nutritional insulin: Administer as rapid-acting insulin (e.g., lispro) in equally divided doses before meals.
- 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.
- If glucose persistently > 140 mg/dL and no episodes of hypoglycemia: Increase basal insulin by 20% and/or increase sliding scale insulin by 2 units.
- In cases of hypoglycemia < 70 mg/dL: Reduce basal insulin by 20% and/or sliding scale insulin by 2 units.
Decrease or hold nutritional insulin if the patient is NPO.
Sliding scale insulin regimen [4]
- 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 | ||
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Insulin sensitive | Usual insulin | Insulin resistant | |
71–140 | 0 | 0 | 0 |
141–180 | 2 | 4 | 6 |
181–220 | 4 | 6 | 8 |
221–260 | 6 | 8 | 10 |
261–300 | 8 | 10 | 12 |
301-350 | 10 | 12 | 14 |
351-400 | 12 | 14 | 16 |
If the blood glucose is < 70 mg/dL, hold all insulin and administer hypoglycemia measures.
Weight-based NPH insulin regimen for glucocorticoid-induced hyperglycemia [5]
- Convert glucocorticoid to equivalent prednisone dose (see glucocorticoids).
- 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) |
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10 | 0.1 |
20 | 0.2 |
30 | 0.3 |
≥ 40 | 0.4 |
NPH doses should be administered in addition to usual basal insulin in patients who are already receiving insulin.
Consider using glargine or detemir in patients receiving dexamethasone. Dexamethasone has a longer hyperglycemic effect than prednisone and most other commonly used systemic glucocorticoids.
Insulin regimens for enteral and parenteral nutrition
Enteral nutrition [6][7]
- 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
- Calculate the total daily nutritional insulin dose:
- 1 unit of insulin per 10–15 g of carbohydrates per day
- or 50–70% of the total daily dose
- Administer as rapid-acting insulin (e.g., lispro) in divided doses every 4–6 hours.
- Calculate the total daily nutritional insulin dose:
- For patients receiving bolus feeding
- Calculate the nutritional insulin dose to cover each meal: 1 unit of insulin per 10–15 g of carbohydrates per meal
- Administer as rapid-acting insulin (e.g., lispro) before each feeding.
- For patients receiving continuous tube feedings
- Add sliding scale insulin as supplemental insulin.
- For patients on continuous tube feedings: Administer rapid-acting insulin (e.g., lispro) every 4 hours or regular insulin every 6 hours.
- For patients receiving bolus feedings: Administer rapid-acting insulin before every meal.
- 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) [6][8]
- 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.