Frequency of hypoglycaemia with basal insulin treatments in adults with type 1 diabetes treated with basal-bolus insulin regimens in treat-to-target trials: A narrative review

Aim: To summarise, in a narrative review, published data on hypoglycaemia occurrence with basal insulin therapy in adults with type 1 diabetes treated with basal-bolus insulin regimens in treat-to-target randomised controlled trials.

Methods: Data were included from 21 eligible trials, which mainly used self-measured blood glucose or plasma glucose to detect hypoglycaemia.

Results: All-day self-measured blood glucose or plasma glucose level 2 (glucose threshold of 3.1 or 3.0 mmol/L) and level 3 (severe, requiring assistance) hypoglycaemic events were reported, respectively, by a range of 69.0%-97.5% and 0%-13.4% adults when receiving basal-bolus insulin therapy, with rates of 10.6-68.1 and 0.0-0.4 events per patient-year of exposure, respectively. Hypoglycaemia rates measured using continuous glucose monitoring (three studies) were numerically, yet consistently, higher than with either other method, except when limiting to symptomatic events. Nocturnal hypoglycaemia rates were generally less than 30% of the equivalent all-day rates.

Conclusions: Differences across the studies in design (e.g., titration targets) and participant characteristics hindered comparison of hypoglycaemia rates by insulin formulation. Consequently, few trends were identified by insulin formulation, study methodology or individuals' characteristics, suggesting that further research is required to identify treatment strategies that facilitate development of individualised recommendations to lower hypoglycaemia risk. These findings are useful to understand hypoglycaemia risk with available basal insulin therapies when used in a multiple daily injection regimen, as well as to provide context for the results of ongoing and future clinical trials, including those for two once-weekly basal insulins, insulin icodec and basal insulin Fc.