Humulin R (Insulin Human (Rdna))

Humulin R is indicated for the management of hyperglycaemia in several diabetic conditions where rapid insulin action is required.

• Type 1 diabetes mellitus, as part of a basal‑bolus insulin regimen to cover meals and correct post‑prandial spikes.
• Type 2 diabetes mellitus, when oral agents are insufficient or when a rapid‑acting insulin is needed for mealtime control.
• Gestational diabetes mellitus, under obstetric supervision, to achieve target maternal glucose levels.
• Inpatient settings for surgical or critical‑care patients requiring intravenous insulin infusion to maintain tight glucose control.
• Adjunct therapy during periods of stress, illness, or steroid use that increase insulin requirements.

• Humulin R contains recombinant human insulin that binds to insulin receptors on muscle, adipose and hepatic cells. Receptor activation triggers the tyrosine kinase cascade, promoting translocation of GLUT‑4 transporters to the cell surface, increasing glucose uptake, and suppressing hepatic gluconeogenesis. The rapid pharmacokinetic profile results in a prompt reduction of circulating glucose after injection. This mimics the physiological insulin surge that follows carbohydrate ingestion, helping to normalize post‑prandial blood glucose levels.

Adverse reactions to Humulin R are reported across a range of frequencies and severities.

Common

• Hypoglycaemia, characterised by sweating, tremor, confusion or loss of consciousness.
• Injection‑site reactions such as erythema, itching or mild swelling.
• Weight gain associated with improved glycaemic control.
• Edema or fluid retention, especially in patients with renal or cardiac impairment.
• Local lipodystrophy or lipoatrophy at repeated injection sites.

Serious

• Severe hypoglycaemia requiring assistance, which can lead to seizures or coma.
• Allergic reactions including urticaria, angio‑edema or anaphylaxis.
• Persistent hyperglycaemia due to insulin resistance or dosing errors.
• Lipodystrophy with significant tissue loss at injection sites.
• Life‑threatening hypoglycaemic events in patients with impaired counter‑regulatory responses.

When prescribing or using Humulin R, clinicians and patients should consider several precautionary measures to minimise risk.

• Monitor blood glucose closely during initiation, dose adjustments, and periods of altered diet or activity.
• Avoid use in patients with known hypersensitivity to human insulin or any excipients.
• Adjust doses in renal or hepatic impairment, as insulin clearance may be reduced.
• Pregnancy and lactation require careful glycaemic targets; consult obstetric guidance.
• Educate patients on recognising and treating hypoglycaemia promptly.
• Be aware of potential lipodystrophy with repeated injections at the same site.
• Do not mix Humulin R with other insulin products unless specifically instructed.

Humulin R may interact with other medicines that affect glucose metabolism or insulin action, requiring dose modifications or monitoring.

Avoid

• Concurrent use of other rapid‑acting insulins or insulin analogues without dose adjustment, which can precipitate severe hypoglycaemia.
• Beta‑blockers, which may mask hypoglycaemia symptoms and prolong recovery.
• High‑dose corticosteroids, which increase insulin resistance and may necessitate higher insulin doses.

Use with caution

• Oral antidiabetic agents such as sulfonylureas or meglitinides, which also lower blood glucose.
• MAO‑A inhibitors, which can potentiate insulin’s glucose‑lowering effect.
• Thiazide diuretics, which may raise blood glucose and require closer monitoring.
• Alcohol consumption, which can cause delayed hypoglycaemia, especially after a dose of insulin.