High-dose thiamine supplementation improves glucose tolerance in hyperglycemic individuals: a randomized, double-blind cross-over trial

Eur J Nutr. 2013 Oct;52(7):1821-4. doi: 10.1007/s00394-013-0534-6. Epub 2013 May 29.


Purpose: To assess the effect of high-dose oral thiamine supplements on glucose tolerance in patients with impaired glucose metabolism.

Methods: Twelve hyperglycemic subjects (10 cases of impaired glucose tolerance and 2 new cases of type 2 diabetes) completed this randomized, double-blind trial, where all participants received both placebo and thiamine capsules (3 × 100 mg/day) for 6 weeks in a cross-over manner. The main endpoint was changes in 2-h plasma glucose. Fasting plasma glucose and insulin, 2-h plasma insulin, the hemostatic model assessment of insulin resistance (HOMA-IR), renal function measurement and thiamin status were also evaluated at the commencement and completion of each treatment period.

Results: Thiamine supplementation resulted in significant decrease in 2-h plasma glucose relative to baseline (8.78 ± 2.20 vs. 9.89 ± 2.50 mmol/l, p = 0.004), with no significant change in the placebo arm. Fasting plasma glucose and insulin, and HOMA-IR increased significantly from baseline after 6 weeks in the placebo arm (p = 0.003, p = 0.04 and p = 0.02, respectively). These variables did not change with thiamine supplementation. There were no significant changes in 2-h plasma insulin or renal function marker, within or between arms.

Conclusion/interpretation: Supplementation with high-dose thiamine may prevent deterioration in fasting glucose and insulin, and improve glucose tolerance in patients with hyperglycemia. High-dose thiamine supplementation may prevent or slow the progression of hyperglycemia toward diabetes mellitus in individuals with impaired glucose regulation.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blood Glucose / metabolism
  • Cross-Over Studies
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Dietary Supplements*
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Fasting
  • Female
  • Glucose Intolerance / drug therapy*
  • Glycated Hemoglobin A / metabolism
  • Humans
  • Insulin / blood
  • Insulin Resistance
  • Male
  • Middle Aged
  • Thiamine / administration & dosage*


  • Blood Glucose
  • Glycated Hemoglobin A
  • Insulin
  • Thiamine