Challenging the 50-50 rule for the basal-bolus insulin ratio in patients with type 2 diabetes who maintain stable glycaemic control.

BACKGROUND: For patients using basal-bolus insulin therapy, it is widespread clinical practice to aim for a 50-50 ratio between basal and total daily bolus. However, this practice was based on a small study of individuals without diabetes. To assess the rule in real-world practice, we retrospectively analyzed patients on basal-bolus therapy that was adjusted at least weekly by an artificial intelligence-driven titration within the d-Nav® Insulin Management Technology. MATERIALS AND METHODS: We obtained de-identified data from the Diabetes Centre of Ulster Hospital for patients with four inclusion criteria: type 2 Diabetes (T2D), on d-Nav >6 months, on basal-bolus insulin therapy >80% of the time (based on insulin analogs), and no gap in data >3 months. RESULTS: We assembled a cohort of 306 patients, followed by the d-Nav service for 3.4 ± 1.8 years (mean ± SD), corresponding to about 180 autonomous insulin dose titrations and about 5000 autonomous individual dose recommendations per patient. After an initial run-in period, mean glycated hemoglobin (HbA1c) values in the cohort were maintained close to 7%. Surprisingly, in just over three-quarters of the cohort, the average basal insulin fraction was <50%; in half of the cohort average basal insulin fraction <41.2%; and in one-quarter the basal insulin fraction was <33.6%. Further, the basal insulin fraction did not remain static over time. In half of the patients, the basal insulin fraction varied by ≥1.9×; and, in 25% of the patients, ≥2.5×. CONCLUSION: Our data show that a 50-50 ratio of basal-to-bolus insulin does not generally apply to patients with T2D who successfully maintain stable glycemia. Therefore, the 50-50 ratio should not serve as an ongoing treatment guide. Moreover, our results emphasize the importance of at least weekly insulin titrations.