Premixed vs basal-bolus insulin regimen in Type 2 diabetes: comparison of clinical outcomes from randomized controlled trials and real-world data.

AIM: To evaluate the concordance between data derived from randomized controlled trial (RCT) and real-world estimates of HbA1c and weight change after 24 weeks of initiation of a basal-bolus compared with a premixed insulin regimen in people with Type 2 diabetes. METHODS: Data eight RCTs were pooled after a systematic review of studies examining basal-bolus (n = 1893) or premixed (n = 1517) regimens. Real-world data were extracted from the UK primary care dataset for people on basal-bolus (n = 7483) or premixed insulin regimens (n=10 744). The mean differences between HbA1c and weight from baseline were calculated using t-tests, while analysis of variance was used to compare the two treatment regimens. Linear regression analyses were used to determine the predictors of this change. RESULTS: Both insulin regimens were associated with HbA1c reductions (real-world data -0.28%; RCT data, -1.4%) and weight gain (real-world data, +0.27 kg; RCT data, +2.96 kg) but there were no significant differences between basal-bolus and premixed insulin. Discordances in the pattern of treatment response were observed, however, between real-world and RCT data for both insulin regimens. For any given baseline HbA1c concentration, the change in HbA1c in the RCTs was greater than in real-world conditions and for those with baseline weight above ~60 kg, RCT data showed overall weight gain in contrast to slight weight loss in the real-world population. Lastly, for both randomized controlled trial and real-world populations, while greater baseline weight was associated with reduced response to treatment, the association was much steeper in the RCT than in the real-world population. In addition, greater baseline weight was associated with greater weight reductions in both premixed insulin and basal-bolus insulin regimens, although to a lesser extent with the latter. CONCLUSION: These results highlight specific discrepancies in the HbA1c reduction and weight change in insulin regimen between real world versus RCT populations; with greater reduction in HbA1c and greater increase in weight observed in the RCT population than in the real-world population. Also, the basal-bolus regimens in both real-world and RCT populations showed greater reduction in HbA1c compared to the premix regimen (though more marked in RCTs), while the premix regimen showed greater increase in weight in real-world, as against basal-bolus in the RCT population.