Compared with insulin glargine, insulin degludec narrows the day-to-day variability in the glucose-lowering effect rather than lowering blood glucose levels

Background: Changes in the day-to-day variability in the glucose-lowering effect of insulin [fluctuations of blood glucose levels (BG) seen during the same time period] that occur when insulin glargine (glargine) is replaced with insulin degludec (degludec) have not been sufficiently evaluated. Subjects: Five diabetics with unstable BG undergoing basal-bolus treatment using insulin glargine as basal insulin. Methods: Basal insulin was changed from glargine to same-dose degludec. The subjects’ HbA1c, glycoalbumin, and 1.5-anhydro-D-glucitol were measured before and after the switchover. Fasting blood glucose concentration (FBG) and predinner blood glucose concentration (PDBG) were measured continuously for 28 days immediately before the switchover, and 28 days immediately thereafter, to compare and evaluate 1) the changes in their mean values and standard deviations (SDs) before and after the switchover, and 2) the frequency of appearance of BG of over 180 mg/dL (BG ≥ 180) and under 70 mg/dL (BG < 70), among other items. Bolus insulin remained completely unchanged. Results: The levels of HbA1c, glycoalbumin, FBG’s mean value, SDs, BG ≥ 180 and BG < 70 all decreased. On the other hand, although PDBG’s SD as well as BG ≥ 180 and BG < 70 decreased, PDBG’s but not FBG’s mean values remained unchanged. The levels of 1.5-anhydro-D-glucitol rose. The mean values of BG ≥ 180 decreased in all subjects. Conclusion: The possibility was shown that degludec, to a greater extent than glargine, suppressed daily fluctuations of FBG and PDBG, suppressed the occurrence frequency of hyperglycemia and hypoglycemia, and exerted more steady hypoglycemic actions.