What is the difference between Isophane (NPH insulin) 40 and Human Mixtard (biphasic insulin) 30/70 in terms of glucose control?

Difference Between Isophane 40 and Human Mixtard 30/70 for Glucose Control

Mixtard 30/70 provides better postprandial glucose control than Isophane (NPH) 40 due to its 30% rapid-acting insulin component, while maintaining similar overall glycemic control.

Composition and Pharmacokinetics

• Isophane insulin (NPH) 40 is an intermediate-acting insulin containing 100% protamine-crystallized insulin, providing primarily basal insulin coverage with no rapid-acting component 1
• Human Mixtard 30/70 is a biphasic insulin containing 30% soluble regular human insulin and 70% isophane (NPH) insulin, providing both prandial and basal coverage in a single injection 2, 3
• The 30% soluble component of Mixtard 30/70 provides faster onset of action for better postprandial glucose control compared to Isophane 40 3, 4

Glycemic Control Differences

Postprandial Glucose Control

• Mixtard 30/70 provides significantly better postprandial glucose control than Isophane 40 due to its rapid-acting component 2, 4
• Studies show that biphasic insulins like Mixtard 30/70 can reduce postprandial glucose by approximately 21.1 mg/dL (1.2 mmol/L) compared to basal-only insulins 5

Fasting Glucose Control

• Isophane 40 may provide more consistent basal coverage throughout the night, potentially resulting in better fasting glucose levels in some patients 1
• However, the 70% intermediate-acting component in Mixtard 30/70 still provides adequate basal coverage for many patients 3, 6

Overall Glycemic Control (HbA1c)

• Both insulins can achieve similar HbA1c levels when properly dosed, though the distribution of glucose control throughout the day differs 2, 3
• Mixtard 30/70 may be more effective for patients who have significant postprandial glucose excursions 6, 4

Clinical Applications

Dosing and Administration

• Isophane 40 is typically administered once or twice daily, primarily targeting basal insulin needs 1
• Mixtard 30/70 is usually administered twice daily, before breakfast and dinner, addressing both basal and prandial needs 2, 3
• Mixtard 30/70 offers the convenience of fewer daily injections compared to separate basal and bolus insulin regimens 2, 6

Patient Selection

• Mixtard 30/70 is more suitable for patients who need both basal and prandial coverage but prefer fewer daily injections 2, 3
• Isophane 40 may be more appropriate for patients who primarily need basal insulin coverage and have minimal postprandial excursions 1
• Patients with significant postprandial hyperglycemia would benefit more from Mixtard 30/70 than from Isophane 40 6, 4

Hypoglycemia Risk

• The risk of nocturnal hypoglycemia may be higher with Isophane 40 due to its peak action occurring during nighttime hours 1
• Mixtard 30/70 may carry a higher risk of daytime hypoglycemia due to its rapid-acting component 3, 6
• Modern analog premixed insulins (like insulin aspart 30/70) have shown reduced nocturnal and major hypoglycemia compared to human premixed insulins like Mixtard 30/70 6

Cost Considerations

• Human insulins like Isophane 40 and Mixtard 30/70 are generally more affordable than analog insulins 1
• The World Health Organization recommends human insulins as first-line options in resource-limited settings due to their cost-effectiveness 1

Special Considerations

• For patients with frequent severe hypoglycemia on human insulins like Isophane 40 or Mixtard 30/70, long-acting insulin analogs may be considered 7, 1
• When switching between different insulin types, close monitoring of blood glucose is essential to adjust dosing appropriately 1
• Proper storage of both insulins is important to maintain potency; unused insulin should be refrigerated while in-use insulin can be kept at room temperature 1