Comparison of thrice daily 'high' vs. 'medium' premixed insulin aspart with respect to evening and overnight glycaemic control in patients with type 2 diabetes.

Background:  The glycaemic control of thrice daily treatment with premixed biphasic insulin aspart (BIAsp) without other antidiabetic therapy was tested in type 2 diabetic patients, in order to compare the glucose control of a ‘high’ mixture (BIAsp 70) or a ‘medium’ mixture (BIAsp 50) (70 or 50% soluble IAsp and 30 or 50% protamine-crystallized IAsp, respectively) administered just before dinner. Aim:  To compare these regimens to conventional 30 : 70 premixture on a twice a day basis. Methods:  This randomized, double-blind, two-period crossover study included 16 patients with type 2 diabetes. Twenty four-hour serum glucose and insulin profiles were obtained thrice: (1) after a one-week run-in period with biphasic human insulin (BHI) 30/70 twice daily (run-in), (2) after 4 weeks of treatment with thrice daily BIAsp 70 before breakfast, lunch and dinner (Dinner70 regimen) and (3) after 4 weeks of BIAsp 70 before breakfast and lunch and BIAsp 50 before dinner (Dinner50). Results:  Daytime average serum glucose was lower with Dinner70 compared to run-in (9.6 ± 0.39 mmol/l vs. 11.2 ± 0.61 mmol/l, p < 0.05). Postprandial glucose excursions after breakfast and lunch were lower, but fasting morning glucose was higher during the treatment periods than in the run-in period. Twenty four-hour C-peptide AUC was considerably lower during both treatment periods than in the run-in period (run-in/Dinner50 ratio 1.29 [1.08; 1.54] p < 0.01; run-in/Dinner70 ratio 1.31 [1.08;1.58], p < 0.01). Conclusions:  Switching the dinner dose to BIAsp 50 did not alter overall glucose control significantly from that provided with BIAsp 70. Exploratory analyses between the two active treatment regimens and run-in/BHI indicate that thrice daily BIAsp 70 administration: (1) for optimization of the night-time control, the dinner dose needs adjustment or replacement by a premixed insulin with a larger proportion of basal insulin than BIAsp 50 and (2) none of the premixtures adequately provide for both the evening meal and overnight requirements.