Vitamin B1 deficiency implicated in diabetic vascular complications

An article published online on August 4, 2007 in the journal Diabetologia concluded that a deficiency of thiamin (vitamin B1) may be the culprit behind the vascular complications of diabetes, one of the most significant problems associated with the disease. Vascular complications of diabetes include heart disease and stroke, as well as microvascular complications such as kidney disease, retinopathy and neuropathy.

Professor Paul Thornalley and associates at the University of Warwick in England compared the red blood cell and plasma thiamin levels of 20 healthy volunteers with 26 individuals with type 1 diabetes and 48 type 2 diabetics. Red blood cell transketolase, which is reduced in thiamin deficiency, and markers of metabolic control and vascular dysfunction were also measured.

The team found that type 1 diabetics had a 76 percent lower, and type 2 diabetics a 75 percent lower plasma thiamin level compared to nondiabetic participants. This deficiency had not been previously discovered among diabetics through the use of the conventional method of evaluating thiamin status by measuring red blood cell levels of transketolase. The normal levels of transketolase found in diabetics were discovered to be the result of an increase in the activity of two thiamin transporter proteins that help transport thiamin into red blood cells as a result of reduced levels of the vitamin.

Low thiamin levels in diabetics were determined to be the result an increased rate of removal of thiamine from the blood into the urine. Renal clearance of the vitamin was in increased 24 fold among type 1 diabetics, and 16 fold in type 2. The decreased availability of thiamin was associated with greater levels of soluble vascular adhesion molecule-1, a marker of vascular complications.

The researchers suggest that future studies evaluate thiamin and its derivatives to correct low plasma concentrations of the vitamin and prevent and/or reverse vascular complications.