Ultra-long-acting insulin analogs [insulin degludec (IDeg) and insulin glargine 300 units/mL (IGla-300)] offer a longer duration of action with less risk of hypoglycemia compared to other long-acting insulins. However, data about the comparative efficacy and safety are inconsistent.
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Four open-label RCTs were included (2727 participants), 3 parallel and 1 cross-over. Overall, the risk of bias assessment yielded some concern or high risk. There was a comparable change in HbA1c from baseline to the end of treatment, a mean difference of 0.07% (95% confidence interval (CI) 0.06 – 0.19; p = 0.29; 3 trials; 2652 patients; very low-certainty evidence), and a comparable rate of any hypoglycemia, rate ratio 1.02 (95% CI 0.8 – 1.3; p = 0.87; 3 trials; 2881 patients; very low-certainty evidence). IDeg resulted in more reduction in FPG compared to IGla-300, mean difference of 10.27 mg/dL (95% CI 7.25 – 13.29; p < 0.001; 3 trials; 2668 patients; low-certainty evidence). Similar rates of nocturnal and severe hypoglycemia were observed, rate ratio of 1.13 (95% CI 0.72 – 1.78; p = 0.54; 3 trials; 2668 patients; very low-certainty evidence) and 1.4 (95% CI 0.41 – 4.73; p = 0.59; 2 trials; 1952 patients; very low-certainty evidence), respectively.
There is no evidence of a difference between IDeg and IGla-300 in the mean change in HbA1c and the risk of anytime, nocturnal, and severe hypoglycemia. IDeg appeared to cause a higher reduction in FPG compared to IGla-300. However, this finding should be interpreted with caution due to the small number of trials included and their high risk of bias.