The Comparative Dosing and Glycemic Control of Intermediate and Long-Acting Insulins in Adult Patients With Type 1 and 2 Diabetes Mellitus

Objective: The various basal insulin products possess differences in pharmacokinetics that can significantly impact glycemic control and total daily basal insulin dosing. In addition, there will be instances where transitions between the different long-acting insulins will need to be made. Because every basal insulin product is not interchangeable on a 1:1 unit-to-unit basis, it is important for health care providers to understand the expected dose adjustments necessary to maintain a similar level of glycemic control. Data Sources: A Medline and Web of Science search was conducted in September 2021 using the following keywords and medical subjecting headings: NPH, glargine, detemir, type 1 diabetes mellitus, and type 2 diabetes mellitus. Study Selection and Data Extraction: Included articles were those that followed adult patients with type 1 diabetes mellitus and/or type 2 diabetes mellitus and compared the following types of insulin: "NPH and glargine," "NPH and detemir," and "glargine and detemir" for at least 4 weeks, had documented basal insulin (BI) doses, and excluded pregnant patients. Data synthesis: Twenty-five articles were found that include adult type 1 and/or type 2 diabetes mellitus patients. Once daily NPH can be converted unit-to-unit to glargine or detemir. Twice daily NPH converted to glargine or detemir requires an initial 20% reduction in BI dose. An increase in dose of BI is recommended when transitioning from glargine to detemir. Glargine and detemir consistently resulted in improved glycemic control with lower incidence of hypoglycemic events compared with NPH. Conclusions: When transitioning between long-acting insulins, the doses are not always interchangeable on a 1:1 basis. Unit dose adjustments are likely if transitioning between BIs and can influence short-term parameters in the acute care setting and long-term parameters in the outpatient setting.