The Rate and Associated Factors of Overbasalization in Patients with Type 2 Diabetes Mellitus in a Tertiary Hospital

Objective: Overbasalization is defined as failing to achieve HbA1c goals despite utilizing basal insulin doses exceeding 0.5 units/kg/day. It is recommended that intensifying treatment for affected patients is considered. However, the available literature on overbasalization is limited. This study aimed to assess the rate of overbasalization and its associated factors in a tertiary hospital. Methods: This cross-sectional study enrolled 454 consecutive patients with type 2 diabetes mellitus (DM) receiving basal insulin, with no changes to their DM treatment in the 3 months before enrollment. Results: Overbasalization was observed in 26 (5.7%) patients in the entire group. The number of patients exhibiting a difference of more than 50 mg/dL in capillary glucose measurements between bedtime and morning was higher in the overbasalization group compared with the non-overbasalization group (P < .001). In logistic regression analysis, the duration of basal insulin usage (B = 0.01, OR = 1.01, 95% CI: 1.005-1.014, P < .001), body mass index (B =-0.095, OR = 0.909, 95% CI: 0.836-0.988, P = .025), and HbA1c level (B = 0.257, OR = 1.294, 95% CI: 1.082-1.547, P = .005) were identified as independent predictive factors for overbasalization. The area under the curve for predicting overbasalization was 0.75 for a basal insulin use duration of 42.5 months. Conclusion: Identifying overbasalization is a practical method for assessing the need for additional treatment options. Clinicians should consider intensifying DM management with appropriate oral antidiabetic drugs or basal-bolus insulin regimens in patients exhibiting overbasalization, especially those who have been on basal insulin for a long time without achieving their treatment goals.