Humulin I (Isophane) (Insulin Human)

Humulin I (Isophane) is indicated for the treatment of diabetes mellitus where basal insulin coverage is required.

• Type 1 diabetes mellitus as part of a basal‑bolus regimen.
• Type 2 diabetes mellitus when oral agents are insufficient.
• Adjunct therapy in gestational diabetes under specialist guidance.
• Combination with rapid‑acting insulin analogues for flexible dosing.
• Pediatric patients with type 1 diabetes when appropriate dosing is established.
• Adults requiring once‑ or twice‑daily intermediate‑acting insulin to maintain fasting glucose control.

• Humulin I (Isophane) contains recombinant human insulin that binds to insulin receptors on cell membranes, activating the intrinsic tyrosine kinase activity of the receptor. This triggers downstream signaling through the PI3‑K/Akt pathway, promoting translocation of GLUT‑4 transporters to the plasma membrane and enhancing glucose uptake in muscle and adipose tissue. It also suppresses hepatic gluconeogenesis, thereby reducing circulating glucose concentrations.

Adverse reactions to Humulin I (Isophane) may vary in frequency and severity.

Common

• Hypoglycemia (low blood glucose) especially if dose is excessive or meals are missed.
• Injection site reactions such as redness, swelling, or itching.
• Lipodystrophy presenting as localized thickening or loss of subcutaneous fat.
• Weight gain associated with improved glycemic control.
• Transient visual disturbances such as blurred vision.
• Nighttime sweating or feeling of weakness.

Serious

• Severe hypoglycemia leading to loss of consciousness or seizures.
• Allergic reactions including urticaria, angioedema, or anaphylaxis.
• Persistent hyperglycemia indicating possible insulin resistance or dosing error.
• Edema or heart failure exacerbation in susceptible patients.
• Hypersensitivity leading to serum sickness‑like reaction.

When prescribing or using Humulin I (Isophane), several precautions should be considered to ensure safe and effective therapy.

• Assess renal and hepatic function, as impairment may prolong insulin action.
• Adjust dose during periods of illness, stress, or changes in physical activity.
• Monitor blood glucose frequently during initiation, dose changes, or when combined with other glucose‑lowering agents.
• Use caution in pregnant or breastfeeding women; consult obstetric guidance.
• Educate patients on recognizing and treating hypoglycemia promptly.
• Avoid injecting into scarred, inflamed, or lipohypertrophic tissue.
• Review concomitant medications that may mask hypoglycemia symptoms.

Humulin I (Isophane) can interact with other medicines, affecting glucose control or insulin action.

Avoid

• Concurrent use of other intermediate‑acting insulins without dose adjustment.
• Beta‑blockers that may mask hypoglycemia symptoms.
• High‑dose corticosteroids that increase insulin resistance.
• MAO inhibitors, due to unpredictable glucose fluctuations.
• Thyroid hormones that may alter insulin metabolism.

Use with caution

• Oral antidiabetic agents (e.g., sulfonylureas, meglitinides) that may potentiate hypoglycemia.
• Thiazide diuretics, which can raise blood glucose levels.
• ACE inhibitors or ARBs, which may enhance insulin sensitivity.
• Alcohol consumption, as it can cause delayed hypoglycemia.
• Non‑steroidal anti‑inflammatory drugs (NSAIDs) that may affect renal function and insulin clearance.
• Beta‑agonists (e.g., albuterol) that can raise blood glucose.