Case Series: Premixed Insulin Dosing in Actual Practice: Two-Thirds in AM, One-Third in PM, or Half and Half?

Abstract

Initiation of insulin in type 2 diabetic patients failing to meet glycemic targets may include addition of either intermediate- or long-acting basal insulin or a biphasic premixed insulin that incorporates both basal and bolus insulins. Dual-acting basal/bolus insulin preparations are administered before meals to improve postprandial glucose levels and provide sustained glucose control throughout the dosing interval. Premixed insulins increase the convenience and acceptability of insulin use by type 2 diabetic patients who are not willing to take on or are not yet candidates for intensive basal/bolus insulin therapy.1,2 The conventional initial approach to dosing premixed insulins (biphasic insulin aspart 70/30, biphasic insulin lispro 75/25, or regular/NPH 70/30) still cited in medical texts and used in general practice is to prescribe a ratio of two-thirds of the total daily insulin dose in the morning before breakfast and one-third in the evening before dinner.3-5 Health care providers in nonspecialty settings may be less likely to use ratios other than two-thirds/one-third because of concerns regarding the safety and effectiveness of a regimen that does not follow this conventional approach. Yet, it is difficult to find practical evidence to guide providers in using a different premixed insulin regimen. After an extensive literature search of published clinical trials of premixed insulins, the authors were unable to reliably determine the ratios used in studies of type 2 diabetic patients in which premixed insulins were compared to each other or compared to basal or bolus insulins alone. No studies examined the actual prescribing patterns of the premixed insulins when used in a realistic clinical specialty practice setting in which endocrinologists use more treat-to-target approaches for rapid dose titration of insulin. This retrospective, observational, descriptive study was designed to examine the use of premixed insulins in a community-based endocrinology practice and …