Incidence of Thiamine Deficiency and Severity of Lactataemia in Patients with Diabetic Ketoacidosis: A Systematic Review

Objective: To perform a systematic literature review summarising current evidence of the incidence and clinical outcomes of thiamine deficiency in patients with diabetic ketoacidosis (DKA). Due to inconsistent and variable measurement of thiamine levels, hyperlactataemia in DKA was included as a potential surrogate for thiamine deficiency. Methods: The protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO). MEDLINE, EMBASE, Cochrane, CINAHL and ClinicalTrials.gov were searched using medical subject headings from database inception to 26 June 2026. Two independent reviewers screened results, and studies were included if they were original research that assessed lactate and/or thiamine in DKA, with subsequent forward citation searching. Risk of bias was assessed using the Cochrane Risk of Bias 2 Tool and the Newcastle-Ottawa Scale, and the data was analysed using a systematic review without meta-analysis (SWIM) approach. Results: Of 2122 screened studies, 31 were included in the final manuscript. Six studies assessed thiamine levels and deficiency, one assessed thiamine replacement, and the remainder assessed hyperlactataemia in patients with DKA. The incidence of thiamine deficiency ranged from 23.8–78%, with two studies demonstrating an inverse correlation between thiamine levels and lactate. The incidence of hyperlactataemia in patients with DKA ranged from 37.5–92%, with inconsistent findings regarding clinical outcomes. Conclusions: The available evidence suggests that thiamine deficiency and hyperlactataemia are common among patients with DKA. However, the association of both with clinical outcomes remains uncertain, with limited data making it difficult to draw significant conclusions, highlighting the need for further research.