In the past, insulin products manufactured by different companies were considered to be incompatible. However, no studies have actually been conducted on insulin product compatibility. The objective of this study was to determine the efficacy and safety of a mixture of insulin products produced by different companies in patients with diabetes mellitus.
Chart reviews were conducted on 105 patients with type 1 diabetes mellitus who were followed up at Taichung Veterans General Hospital between October 1999 and December 2001. Twenty patients were included for final analysis. The average daily insulin requirement, hemoglobin A1c (HbA1c) level, body weight, and body mass index (BMI) were compared 6 months before (period 1, used same brand of insulin, Humulin N plus Humulin R) and after (period 2, used different brands of insulin, Insulatard HM plus Humulin R) the mixture treatment. Hypoglycemia and other adverse events were also recorded.
The difference in average daily insulin requirement (intermediate-acting, short-acting) between periods 1 and 2 was not statistically significant (27.1 ± 10.8 U vs 27.1 ± 10.8 U, p = 0.317; 13.9 ± 7.6 U vs 14.7 ± 7.3 U, p = 0.655). There was no significant difference in HbA1c level between periods 1 and 2 (8.0 ± 1.5% vs 8.0 ± 1.2%, p = 0.732). The difference in BMI between periods 1 and 2 was not statistically significant. The number of hypoglycemic events 6 months before and after the mixture therapy was also not statistically significantly different. There were no reported injection-site reactions or an increased number of adverse events when using the mixture of Insulatard HM and Humulin R.
This retrospective study demonstrated that using a mixture of different brands of insulin (Insulatard HM plus Humulin R) for 6 months did not change the efficacy of insulin in patients with type 1 diabetes mellitus.