Humulin R (Regolare) (Insulin Human (Rdna))

Humulin R is indicated for the management of hyperglycaemia in adults and children with diabetes mellitus.

• Initiation of basal‑bolus insulin therapy in type 1 diabetes, typically combined with carbohydrate counting.
• Supplemental rapid‑acting insulin for mealtime glucose control in type 2 diabetes, often used when oral agents are insufficient.
• Adjustment of insulin dose during periods of illness, stress, or changes in diet, guided by frequent blood‑glucose monitoring.
• Use in hospital or outpatient settings where a short‑acting insulin is required for intravenous or subcutaneous administration.
• Replacement therapy when endogenous insulin production is insufficient, such as after pancreatectomy or in advanced diabetes.

• Humulin R consists of recombinant human insulin that binds to insulin receptors on muscle, adipose and hepatic cells. Receptor activation triggers autophosphorylation of the β‑subunit, initiating the PI3‑K/Akt signaling cascade that promotes translocation of GLUT‑4 transporters to the cell surface, increasing glucose uptake. In the liver, insulin suppresses gluconeogenesis and glycogenolysis, thereby lowering circulating glucose levels. The rapid onset of action reflects its short absorption time after subcutaneous injection.

Adverse reactions to Humulin R may vary in frequency and severity.

Common

• Hypoglycaemia, manifested by sweating, tremor, or confusion.
• Injection‑site reactions such as redness, swelling, or itching.
• Lipodystrophy, including lipohypertrophy at repeated injection sites.
• Mild weight gain associated with improved glycaemic control.
• Nausea or abdominal discomfort reported occasionally.
• Transient visual disturbances such as blurred vision during rapid glucose shifts.

Serious

• Severe hypoglycaemia leading to loss of consciousness or seizures.
• Allergic reactions ranging from urticaria to anaphylaxis.
• Edema or heart failure exacerbation in susceptible patients.
• Persistent hyperglycaemia indicating possible insulin resistance.
• Severe allergic response presenting as angio‑edema of the face, lips, or tongue.
• Acute pancreatitis manifested by upper abdominal pain and elevated enzymes.

When prescribing Humulin R, clinicians should consider several precautionary measures to minimise risks and optimise therapy.

• Assess renal and hepatic function, as impairment may alter insulin clearance.
• Adjust dose in patients with fluctuating dietary intake or physical activity.
• Monitor for hypoglycaemia in elderly, pregnant, or fasting individuals.
• Educate patients on proper injection technique to avoid lipohypertrophy.
• Review concomitant medications that may potentiate or mask hypoglycaemia.
• Use caution in patients with a history of cardiovascular disease or heart failure.
• Store the product according to label instructions; avoid freezing.

Humulin R may interact with other agents that affect glucose metabolism or insulin action.

Avoid

• Concurrent use of high‑dose sulfonylureas that can precipitate severe hypoglycaemia.
• Administration of glucagon or beta‑agonists during an insulin overdose.
• Mixing Humulin R with other insulin formulations not specifically approved for co‑administration.
• Use of MAO inhibitors is not recommended as they may interfere with insulin metabolism.

Use with caution

• Beta‑blockers, which may mask hypoglycaemic symptoms.
• Corticosteroids, which can increase insulin resistance and require dose adjustments.
• Diuretics, especially thiazides, that may elevate blood glucose.
• Oral antidiabetic agents such as metformin, where combined therapy necessitates close monitoring.
• Alcohol consumption can potentiate insulin’s glucose‑lowering effect and increase hypoglycaemia risk.