Actrapid HM Penfill 100 I.U. is a fast-acting human insulin solution used to manage blood glucose levels in patients with diabetes mellitus. Each cartridge contains 3 mL of clear, colorless solution, with 300 units of insulin. Designed for subcutaneous or intravenous injection, it mimics natural insulin, facilitating glucose uptake in muscles and fat, and preventing glucose production by the liver. Onset of action occurs within 30 minutes, peaking at 1.5-3.5 hours, and lasting up to 7-8 hours. This insulin penfill is suitable for use in insulin pens, offering precise dosing and ease of administration. It is essential for controlling blood sugar levels to prevent diabetes-related complications.