Myths vs facts: Transferrin and Blutzucker

Transferrin is an iron transport protein and not a direct marker for blood sugar. A common myth is that high transferrin indicates diabetes – this is incorrect. Transferrin and its saturation primarily reflect iron status (deficiency or overload). However, there is a mechanistic link between iron metabolism and glucose metabolism: iron overload can promote oxidative stress and worsen insulin resistance, while iron deficiency can impair glucose tolerance. Studies show associations between elevated ferritin (iron stores) and type 2 diabetes risk, but transferrin alone is not a clinical predictor. For blood sugar assessment, fasting glucose, HbA1c, and oral glucose tolerance tests are standard. Caveat: In iron deficiency, transferrin is often elevated, which could be falsely associated with diabetes. The evidence for a direct link between transferrin and blood sugar is weak, based on mechanistic and epidemiological data, not randomized trials. Therefore, transferrin should not be interpreted as a blood sugar marker.