Insulatard 100IU/ml Flexpen contains Insulin Isophane, a human insulin analogue formulated at a concentration of 100 IU/ml, designed for the management of diabetes mellitus requiring insulin therapy. This intermediate-acting insulin provides a prolonged onset and duration of action, facilitating basal glycaemic control by mimicking endogenous insulin release. Insulatard is administered subcutaneously using the Flexpen device, which allows for accurate and convenient dosing. The pharmacokinetic profile typically results in onset of action within 1 to 2 hours, peak activity between 4 to 12 hours, and duration lasting up to 24 hours, thereby supporting once or twice daily dosing regimens. It is indicated for patients with type 1 diabetes mellitus and for those with type 2 diabetes mellitus when oral hypoglycaemic agents are insufficient to achieve glycaemic targets. Dose individualization is essential, based on blood glucose monitoring and patient response, to minimize the risk of hypoglycaemia. Insulatard should be used as part of a comprehensive diabetes management plan including diet, exercise, and regular glucose monitoring. Caution is advised in patients with renal or hepatic impairment. Proper injection technique and storage conditions must be adhered to ensure efficacy and safety.