Premixed insulin preparations and glycaemic control in type 1 diabetes mellitus

The role of premixed insulin preparations in Type 1 DM remains unresolved. The degree of glycaemic control achieved with the use of premixed insulin preparations in an unselected group of subjects with Type 1 DM has not previously been reported. We abstracted and reviewed data on 600 subjects with Type 1 diabetes mellitus in our computer data base. 134 (23%) were taking two injections of premixed insulin daily. In these subjects glycaemic control as assessed by the most recent HbA1c measurement was 7.6 +/- 0.1% vs 7.4 +/- 0.1% in those subjects on separate insulins, p = N.S. In those subjects aged < 35 years, 62/220 (28%) used premixed insulin. HbA1c was higher in those on premixed insulin 7.8 +/- 0.2% and 7.2 +/- 0.1%, p < 0.05. This difference in HbA1c was seen only in those subjects with diabetes duration of 3 to 8 years (n = 78) where HbA1c was higher in those subjects on premixed insulin, 8.4 +/- 0.5% versus 6.9 +/- 0.2%, p < 0.01. In subjects aged > 35 years, 74/318 (23%) used premixed insulin. HbA1c did not differ between those using premixed insulin and those using separate insulin preparations, 7.5 +/- 0.2% and 7.5 +/- 0.1% respectively. We conclude that use of premixed insulin preparations achieved a similar level of glycaemic control as use of individual insulin preparations with the exception of patients aged less than 35 years who were 3 to 8 years following diagnosis. The relatively good glycaemic control achieved may make these preparations a useful alternative to multiple injection therapy for many patients with Type 1 DM.