Insulatard Penfill 100 IU/ml Suspension for Injection is a long-acting insulin preparation used to control blood glucose levels in individuals with diabetes mellitus. Manufactured by Novo Nordisk, this formulation contains isophane (NPH) insulin, which has a gradual onset and extended duration of action. The insulin starts to lower blood glucose approximately 1.5 hours after injection, with its effects lasting up to 24 hours. It is commonly administered subcutaneously in the thigh, abdominal wall, gluteal region, or deltoid region, with injection sites rotated within the same anatomical area to minimize the risk of lipodystrophy. Insulatard Penfill is often used in combination with rapid-acting insulins to achieve optimal glycemic control. Patients should consult their healthcare provider for personalized dosing and administration instructions.