Thiamine Deficiency in Diabetes: Implications for Diabetic Ketoacidosis

Diabetic ketoacidosis (DKA) remains a life-threatening complication of diabetes mellitus with suboptimal outcomes despite standard management. Emerging evidence suggests that thiamine (vitamin B1) deficiency may play an under-recognized role in DKA pathophysiology and clinical course. This narrative review synthesizes current evidence regarding thiamine deficiency in diabetes and DKA, examining molecular mechanisms, clinical implications, and the rationale for thiamine supplementation as adjunctive therapy. Thiamine deficiency is highly prevalent in diabetes, with plasma concentrations reduced by approximately 75% compared to healthy controls. In DKA specifically, 25–35% of patients present with thiamine deficiency, which often worsens during insulin therapy. The primary mechanism involves hyperglycemia-induced downregulation of renal thiamine transporters (THTR-1 and THTR-2), resulting in 16–24-fold increased renal clearance and massive urinary losses. Thiamine pyrophosphate serves as an essential cofactor for three critical enzymes in glucose metabolism: pyruvate dehydrogenase, α-ketoglutarate dehydrogenase, and transketolase. Deficiency impairs these pathways, causing pyruvate accumulation with conversion to lactate (resulting in lactic acidosis), compromised TCA cycle function (reducing ATP production by 40–48%), and decreased NADPH generation (increasing oxidative stress). Clinical manifestations include persistent metabolic acidosis despite standard therapy, myocardial dysfunction with elevated cardiac biomarkers, neurological impairment, and prolonged recovery times. Cellular studies demonstrate that thiamine supplementation significantly improves mitochondrial oxygen consumption in DKA patients. The high prevalence of thiamine deficiency in DKA, compelling biochemical rationale, excellent safety profile, and preliminary mechanistic evidence support the urgent need for large-scale randomized controlled trials examining thiamine supplementation to definitively establish efficacy, optimal dosing, and patient selection criteria.