Insulin

# insulin ## Overview - **Classification**: Antidiabetic agent, hormone (polypeptide). - **Mechanism**: Binds to insulin receptors, facilitating glucose uptake into cells (muscle, adipose), inhibits hepatic glucose production, and promotes glycogen storage. ## Primary Indications 1. **Type 1 Diabetes Mellitus (T1DM)** - Essential for survival, provides exogenous insulin. 2. **Type 2 Diabetes Mellitus (T2DM)** - When oral agents or other injectables are insufficient to achieve glycemic targets. 3. **Diabetic Ketoacidosis (DKA) / Hyperosmolar Hyperglycemic State (HHS)** - Correction of hyperglycemia and acidosis. 4. **Hyperkalemia** - Drives potassium intracellularly (given with glucose). ## Adult Dosing ### Standard Dosing **Type 1 Diabetes Mellitus (Initial)** - **Dose**: Typically **0.5-1 Unit/kg/day** Total Daily Dose (TDD). - **Frequency**: Divided into basal (long-acting) and prandial (rapid/short-acting) components. - **Route**: Subcutaneous (SC) injection. - **Special Considerations**: Highly individualized, titrate based on glucose readings. **Type 2 Diabetes Mellitus (Basal Insulin Initiation)** - **Dose**: Start with **10 units daily** or **0.1-0.2 Units/kg/day**. - **Frequency**: Once daily (long-acting) or twice daily (intermediate-acting). - **Route**: Subcutaneous (SC) injection. - **Special Considerations**: Titrate by 2-4 units every 2-3 days until fasting glucose target is met. **Diabetic Ketoacidosis (DKA) / Hyperosmolar Hyperglycemic State (HHS)** - **Dose**: **0.1 Units/kg IV bolus** (regular insulin), followed by **0.1 Units/kg/hour IV continuous infusion**. - **Frequency**: Continuous infusion. - **Route**: Intravenous (IV). - **Special Considerations**: Adjust infusion rate to decrease glucose by **50-75 mg/dL/hour**. Add dextrose when glucose is <200-250 mg/dL. **Hyperkalemia** - **Dose**: **10 Units regular insulin IV** (given with **25 grams dextrose IV**). - **Frequency**: Once, or repeat as clinically indicated. - **Route**: Intravenous (IV). - **Special Considerations**: Dextrose prevents hypoglycemia. Onset of action <1 hour, duration 4-6 hours. ### Dose Adjustments - **Renal Impairment**: Insulin clearance is reduced. Requires significant dose reduction (often **25-50%**) if eGFR <50 mL/min/1.73m². Close monitoring essential. - **Hepatic Impairment**: Reduced hepatic insulin degradation. May require dose reduction. Monitor glucose closely. - **Elderly Patients**: Increased risk of hypoglycemia. Start low, titrate slow ("start low, go slow"). May require lower doses due to decreased food intake, renal function. ## Pediatric Dosing ### Neonates (0-28 days) - **Indication**: Hyperglycemia (e.g., associated with critical illness, parenteral nutrition). - **Dose**: **0.01-0.05 Units/kg/hour** (regular insulin). - **Frequency**: Continuous IV infusion. - **Maximum**: Highly individualized; titrate to maintain blood glucose target. - **Special Notes**: Always use an infusion pump. Very close glucose monitoring essential to prevent hypoglycemia. ### Infants (1-12 months) - **Indication**: Type 1 Diabetes Mellitus (T1DM) initial. - **Dose**: **0.2-0.5 Units/kg/day** TDD. - **Frequency**: Basal-bolus regimen, divided into basal and prandial doses. - **Maximum**: TDD rarely exceeds **0.8 Units/kg/day**. - **Special Notes**: Caregiver education vital for administration and hypoglycemia management. - **Indication**: Diabetic Ketoacidosis (DKA) / Hyperosmolar Hyperglycemic State (HHS). - **Dose**: **0.05-0.1 Units/kg/hour** (regular insulin). - **Frequency**: Continuous IV infusion. - **Maximum**: Infusion rates typically do not exceed **0.1 Units/kg/hour**. - **Special Notes**: **No IV bolus** recommended in DKA in children; start directly on infusion to reduce risk of cerebral edema. ### Children (1-12 years) - **Indication**: Type 1 Diabetes Mellitus (T1DM) initial. - **Dose**: **0.5-1 Units/kg/day** TDD (higher during puberty, often **0.8-1.2 Units/kg/day**). - **Frequency**: Basal-bolus regimen, divided. - **Maximum**: TDD can reach **1.5 Units/kg/day** during peak puberty. - **Special Notes**: Dosing needs change with growth spurts and puberty. - **Indication**: Diabetic Ketoacidosis (DKA) / Hyperosmolar Hyperglycemic State (HHS). - **Dose**: **0.05-0.1 Units/kg/hour** (regular insulin). - **Frequency**: Continuous IV infusion. - **Maximum**: Infusion rates typically do not exceed **0.1 Units/kg/hour**. - **Special Notes**: **No IV bolus** recommended; start directly on infusion. ### Adolescents (13-18 years) - **Indication**: Type 1 Diabetes Mellitus (T1DM). - **Dose**: Often **0.8-1.2 Units/kg/day** TDD due to hormonal changes. - **Frequency**: Basal-bolus regimen. - **Maximum**: Can approach **1.5 Units/kg/day** TDD, similar to adult high-dose needs. - **Special Notes**: Dosing approach is similar to adults, but consider adherence challenges. ## Safety Information ### Contraindications - **Absolute**: Hypoglycemia (current episode). - **Absolute**: Hypersensitivity to insulin or any excipients. ### Common Adverse Effects - **Very Common (>10%)**: Hypoglycemia (low blood sugar). - **Common (1-10%)**: Injection site reactions (redness, swelling, itching), lipodystrophy (fat atrophy/hypertrophy at injection site), weight gain, peripheral edema. - **Serious but Rare**: Anaphylaxis (severe allergic reaction), severe hypoglycemia (leading to seizures, coma, permanent brain damage). ### Key Drug Interactions - **Beta-blockers**: Can mask symptoms of hypoglycemia (e.g., tremor, palpitations) and delay recovery from hypoglycemia. - **Corticosteroids, Diuretics, Sympathomimetics**: May increase blood glucose, requiring increased insulin doses. - **Oral Hypoglycemics (e.g., Sulfonylureas, Metformin), ACE Inhibitors, MAOIs, Salicylates**: May increase the risk of hypoglycemia. - **Alcohol**: Can enhance the glucose-lowering effect of insulin and increase the risk of delayed hypoglycemia. ## Monitoring & Follow-up - **Before Treatment**: Baseline A1c, fasting plasma glucose, renal function (creatinine, eGFR). - **During Treatment**: - **Self-monitoring Blood Glucose (SMBG)**: Multiple times daily (e.g., pre-meal, bedtime, post-meal) depending on regimen. - **Continuous Glucose Monitoring (CGM)**: If applicable, provides trend data. - **HbA1c**: Every 3-6 months. - **Potassium**: Crucial during IV insulin infusions (e.g., DKA) due to risk of hypokalemia. - **Clinical Signs**: Watch for symptoms of hypoglycemia (sweating, tremor, confusion, hunger, dizziness) and hyperglycemia (polyuria, polydipsia, blurred vision, fatigue). ## Clinical Pearls - 💡 **Always have rescue glucose (e.g., glucose tablets, juice) readily available** for treating mild-moderate hypoglycemia. - 💡 **Rotate injection sites** within an anatomical region (e.g., abdomen) to prevent lipodystrophy and ensure consistent absorption. - 💡 **Educate patients on proper insulin storage** (refrigerated for unopened vials/pens, room temperature for opened/in-use). - 💡 **Insulin units are not interchangeable with volume (mL) or weight (mg)**; always use appropriate insulin syringes (U-100) or pens. - 💡 **Never share insulin pens or syringes** due to risk of blood-borne pathogen transmission. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.