Insulin Isophane 50% + Human insulin 50%
Overview
Insulin Isophane 50% + Human Insulin 50% is a biphasic premixed insulin formulation combining equal proportions of intermediate-acting insulin isophane and short-acting human regular insulin. The human insulin component facilitates rapid glucose uptake into peripheral tissues and suppresses hepatic glucose production following meals, helping to control postprandial blood glucose levels. The insulin isophane component, formulated with protamine to delay absorption, provides sustained basal insulin activity that supports glycemic control between meals and overnight. Together, this combination mimics physiological insulin secretion patterns more closely than single-component insulin therapy. It is administered via subcutaneous injection and is commonly used in patients who require both basal and mealtime insulin coverage but prefer a simplified dosing regimen. This formulation has been widely used in diabetes management for decades and remains relevant in clinical practice, particularly in settings where cost-effective and predictable insulin action is required.
Background and Date of Approval
Recombinant human insulin was first approved by the United States Food and Drug Administration in October 1982, marking a major advancement in diabetes treatment. Insulin isophane and human regular insulin formulations were subsequently developed into premixed biphasic combinations, including the 50% insulin isophane and 50% human insulin ratio, to simplify insulin therapy while maintaining effective glycemic control. These premixed formulations gained regulatory approvals across multiple regions during the late 1980s and 1990s as part of established diabetes treatment protocols. They have since been authorised by regulatory bodies including the FDA, EMA, and national authorities worldwide under various brand names. Their long-standing approval is supported by extensive clinical use and evidence demonstrating effective and reliable blood glucose control in both type 1 and type 2 diabetes mellitus.
Uses
Insulin Isophane 50% + Human Insulin 50% is indicated for the treatment of patients with type 1 diabetes mellitus and for patients with type 2 diabetes mellitus who require insulin therapy to achieve adequate glycemic control. It is typically used when both basal insulin coverage and prandial glucose control are needed within a simplified injection schedule. The formulation may be used as monotherapy or as part of a broader diabetes management plan that includes dietary modification, physical activity, and regular blood glucose monitoring.
Administration
This insulin combination is administered by subcutaneous injection into areas such as the abdomen, thigh, buttocks, or upper arm, with systematic rotation of injection sites to reduce the risk of lipodystrophy. The suspension must be gently mixed before injection to ensure uniform distribution of insulin components. It is usually administered 15 to 30 minutes before meals, once or twice daily depending on individual glycemic patterns. Dosage is individualized based on body weight, blood glucose levels, meal timing, and insulin sensitivity, and ongoing glucose monitoring guides dose adjustments throughout treatment.
Side Effects
The most common side effect associated with Insulin Isophane 50% + Human Insulin 50% is hypoglycemia, which may present with symptoms such as sweating, tremor, palpitations, hunger, dizziness, or confusion. Injection site reactions including redness, pain, swelling, or itching may occur. Weight gain can be observed as glycemic control improves. These effects vary among patients and are generally manageable with appropriate education, monitoring, and dose adjustments.
Warnings
Serious adverse events include severe hypoglycemia, which can lead to loss of consciousness or seizures if untreated, and hypokalemia resulting from insulin-mediated potassium shifts. Allergic reactions ranging from localized injection site responses to rare systemic hypersensitivity reactions have been reported. Insulin therapy should not be initiated or continued during episodes of hypoglycemia. Caution is required in patients with renal or hepatic impairment, as insulin clearance may be reduced, increasing the risk of prolonged hypoglycemia.
Precautions
Prior to initiating therapy, baseline assessment of blood glucose control, renal function, hepatic function, and concurrent medications is recommended. Drugs such as other antidiabetic agents, beta-blockers, corticosteroids, alcohol, and medications affecting insulin sensitivity can influence glycemic response and hypoglycemia risk. Patients should be counselled on consistent meal timing, physical activity patterns, and recognition of hypoglycemia symptoms. Insulin requirements may change during illness, stress, pregnancy, or changes in diet or activity level, requiring careful monitoring and dose adjustment.
Expert Tips
Effective use of Insulin Isophane 50% + Human Insulin 50% requires individualised patient assessment and education. Ensure patients understand correct injection technique, site rotation, and timing relative to meals. Regular review of self-monitored blood glucose records helps optimise dosing and reduce hypoglycemia risk. Emphasise the importance of carrying a fast-acting glucose source and recognising early signs of low blood sugar. Collaboration with diabetes educators and dietitians can improve adherence and long-term glycemic outcomes.