Does an insulin pen improve the metabolic control of type 1 diabetes mellitus if added to conventional treatment?
This study concerns the metabolic control of 19 type 1 diabetic patients during 3 consecutive periods of 4 months. All patients were well trained in self-control and self-regulation. During the first period, the previous treatment regimen consisting of diet and injections once or twice daily of short-acting and intermediate-acting insulin was intensified. During the 2nd period, an insulin pen, filled with short-acting insulin, was added to the treatment. The patients were advised to use this pen every time the blood glucose concentration exceeded 10 mmol/l or when this was expected; extra attention was paid to the lunch time and afternoon snacks. During the 3rd period, the use of the insulin pen was stopped but, just as in the 1st period, adjustments with short-acting insulin using normal syringes were allowed. The total daily dose of insulin remained unchanged throughout the entire study. The relative proportion of short-acting insulin increased from 25 to 34%, a quarter of which was injected by the insulin pen during period 2. The HbA1 % decreased steadily from 12.8 +/- 2.0 to 10.6 +/- 1.3 (P less than 0.001) during the first 2 periods and remained unchanged thereafter. The blood glucose concentration measured 7 times during the day twice monthly showed the greatest fall during the 1st period with only a minor extra fall during the 2nd period, and no further statistical drop during the last period. None of the patients had any problems using the insulin pen and 15 of 19 patients resumed its use after the end of the study. It is concluded that the improvement of glycaemic control was due to the intensified attention and not to the use of the insulin pen per se.