Medication Adherence in Type 2 Diabetes—A Study Using Direct Blood Analysis

Introduction and Objective: Approximately 25% of patients fail to take their prescribed medications, but true adherence to specific drugs and the underlying reasons for non-adherence remain unclear. This is due to the complexity of adherence assessments, as questionnaires are unreliable and provide limited information, while direct methods based on drug detection in blood are rarely used. Here we evaluated medication adherence in Czech patients with type 2 diabetes using a direct method. Methods: We analyzed the blood of 546 patients for various drugs, including 13 antidiabetics, and compared the results with their prescribed medications. Blood samples were collected during routine outpatient visits, where patients also completed a questionnaire on lifestyle, side effects, and medication use. Results: Adherence to metformin was high, with the drug undetected in only 2.4% of patients and subtherapeutic levels (<100 ng/mL) found in an additional 5.3%. Lower adherence (~10%) was observed for gliptins (dipeptidyl peptidase-4 inhibitors) and sulfonylurea analogs. The lowest adherence among antidiabetic medications was recorded for gliflozins (sodium-glucose cotransporter-2 inhibitors), undetected in 25% of patients. Non-adherence was often partial, with many patients taking some prescribed medications while skipping others, particularly gliflozins. This partial non-adherence correlated with worse clinical outcomes, as non-adherent patients had higher glucose levels and HbA1c compared to adherent ones. Non-adherence was not linked to any lifestyle factors but was influenced by medication type and the number of prescribed drugs. Conclusion: This study highlights that non-adherence to treatment is often partial, with patients selectively omitting specific drugs, leading to worse clinical outcomes. These findings emphasize the need for strategies to improve adherence to drug classes patients commonly avoid and to promote the use of fixed drug combinations. Disclosure: V. Skop: None. I. Lankova: None. S. Antalová: None. K. Mala-Ladova: None. J. Maly: None. T. Pelikanova: None. T. Cajka: None. M. Haluzik: Research Support; Sanofi. Advisory Panel; Eli Lilly and Company. Speaker's Bureau; Novo Nordisk, Abbott. Advisory Panel; AstraZeneca. Speaker's Bureau; GlaxoSmithKline plc, Amgen Inc. Advisory Panel; Bausch Health. Funding: Funded by the EU ? Next Generation EU, LX22NPO5104;Ministry of Health of the Czech Republic - NU20-01-00186;project RVO - IKEM, ID 00023001