The choice of the insulin basal rate regimen at initiation of insulin pump therapy in routine clinical practice

Background: Numbers of patients with diabetes mellitus using insulin pumps have been increasing every year. Successful achievement of glycemic targets with continuous subcutaneous insulin infusion (CSII) is based on an adequate basal rate of infusion, carbohydrate coefficient and insulin sensitivity index. There are two approaches to basal insulin infusion rate, namely the flat one and the circadian; however, at present there is no convincing data on which one should be chosen at the start of insulin pump therapy.

Aim: To compare two regimens of basal insulin infusion rate at initiation of insulin pump therapy in routine clinical practice.

Materials and methods: We analyzed data from 120 patients with Type 1 diabetes mellitus, who were switched on insulin pump therapy in the Department of Endocrinology from 2017 to 2018. At initiation of CSII, 60 patients used the flat basal rate profile and the other 60 patients used the circadian basal rate, calculated with the Renner's scale. Safety of the two basal rate regimens was assessed based on glucose variability measured with continuous glucose monitoring during the first two days after the start of insulin pump therapy.

Results: Mean (± SD) coefficients of variation in the groups with circadian and flat basal rate at Day  1 were 31.06±12.13 and 32.74±10.7, respectively (p=0.423); at Day 2, 26.78±11.27 and 28.83±10.7 (p=0.309). Median [Q1; Q3] areas under glucose curve (AUC) values above the glucose targets in the groups with circadian and flat basal rate at Day 1 were 0.37 [0.03; 0.89] and 0.48 [0.08; 1.75], respectively, at Day 2 0.44 [0.03; 1.57] and 0.31 [0.1; 1.5], respectively (p>0.05). Median glucose AUC values below the goal in groups with circadian basal rate and flat basal rate on the first day were 0.01 [0; 0.06] and 0.02 [0; 0.1], respectively (p=0.855), on the second day – 0.00 [0; 0.01] and 0.00 [0; 0.02], respectively (р=0.085). We also haven’t found any between-group differences in the prevalence of glucose deviations below and above the target, as well as in the time spent in normoglycaemia.

Conclusion: The comparative analysis of two basal insulin rate regimens in Type 1 diabetic patients switched to insulin pump therapy has shown no significant differences between them. The use of Renner’s scale has no clinical advantages over the fixed basal insulin regimen at initiation of insulin pump therapy in adults.