Levemir 100IU/ml Flexpen contains insulin detemir, a long-acting basal insulin analog indicated for the treatment of diabetes mellitus in adults, adolescents, and children aged 2 years and above. Insulin detemir provides a consistent and prolonged glucose-lowering effect, mimicking the basal insulin secretion of a healthy pancreas. It is administered subcutaneously once or twice daily to improve glycemic control in patients with type 1 or type 2 diabetes. Levemir Flexpen is a prefilled, disposable insulin delivery device designed for ease of use, allowing precise dosing in units. The pharmacokinetic profile of insulin detemir ensures a relatively flat and predictable action profile with a duration of up to 24 hours, reducing the risk of nocturnal hypoglycemia compared to intermediate-acting insulins. Dose adjustments should be individualized based on blood glucose monitoring and patient response. Levemir should not be mixed with other insulins or diluted, as this may alter its pharmacodynamic properties. Common adverse effects include hypoglycemia, injection site reactions, and lipodystrophy. Patients should be educated on proper injection technique, storage conditions, and recognition and management of hypoglycemia. Levemir Flexpen is contraindicated in patients with hypersensitivity to insulin detemir or any excipients.