Humulin R (Insulin Human (Rdna))

Humulin R is indicated for the treatment of diabetes mellitus in both adults and children.

• Type 1 diabetes mellitus, as basal or mealtime insulin.
• Type 2 diabetes mellitus, when diet, exercise, and oral agents are insufficient.
• Management of hyperglycemia during pregnancy (gestational diabetes) under medical supervision.
• Use in hospital settings for intravenous insulin infusion when rapid glucose control is required.
• Adjunct therapy during surgery or critical illness to maintain target blood glucose levels.

• Humulin R consists of recombinant human insulin that binds to insulin receptors on the surface of muscle, adipose, and hepatic cells. Receptor activation triggers autophosphorylation and downstream signaling through the PI3‑kinase/Akt pathway, promoting translocation of GLUT‑4 transporters to the cell membrane and increasing glucose uptake. In the liver, insulin suppresses gluconeogenesis and glycogenolysis, thereby lowering overall circulating glucose concentrations significantly.

Adverse reactions to Humulin R are categorized by frequency and clinical severity.

Common

• Mild hypoglycemia, characterized by sweating, tremor, palpitations, hunger, or anxiety, typically occurring shortly after injection.
• Localized injection‑site reactions including erythema, swelling, pruritus, or induration that resolve within a few days.
• Lipodystrophy, manifested as either lipoatrophy (fat loss) or lipohypertrophy (fat accumulation) at sites used repeatedly for administration.
• Transient weight gain, often modest, associated with improved glucose utilization and fluid retention.

Serious

• Severe hypoglycemia leading to neuroglycopenic symptoms such as confusion, seizures, loss of consciousness, or coma.
• Allergic responses ranging from generalized urticaria and angioedema to life‑threatening anaphylaxis requiring emergency treatment.
• Fluid overload or exacerbation of pre‑existing heart failure, presenting as peripheral edema, shortness of breath, or rapid weight gain.

When prescribing or using Humulin R, clinicians and patients should consider several safety precautions.

• Assess renal and hepatic function, as impairment may prolong insulin action and increase hypoglycemia risk.
• Adjust doses during periods of reduced food intake, illness, or increased physical activity to avoid low blood glucose.
• Monitor blood glucose closely during pregnancy, as insulin requirements can change rapidly.
• Educate patients on proper injection technique and site rotation to minimize lipodystrophy.
• Review concomitant medications that affect glucose metabolism, such as sulfonylureas or beta‑blockers.
• Caution in patients with a history of cardiovascular disease or heart failure due to potential fluid retention.

Humulin R may interact with other medicines, altering its glucose‑lowering effect or increasing adverse reactions.

Avoid

• Concurrent use of other rapid‑acting insulins or high‑dose sulfonylureas, which can cause severe hypoglycemia.
• Beta‑adrenergic antagonists that mask hypoglycemia symptoms, making detection difficult.

Use with caution

• Oral antihyperglycemics (e.g., metformin, thiazolidinediones) that may potentiate insulin’s effect.
• Corticosteroids, which raise blood glucose and may require higher insulin doses.
• Diuretics, especially thiazides, that can affect electrolyte balance and glucose control.
• Alcohol consumption, which can cause unpredictable glucose fluctuations.