Effect of Blood Donation in the Glycemic Control of Prediabetic Donors: A Blinded Randomized Controlled Trial

Excess body iron has been associated with hepatic insulin resistance and impaired glucose regulation. Whether mild iron reduction through blood donation benefits individuals with prediabetes remains uncertain. This study examined the metabolic effects of a single blood donation in overweight prediabetic donors.

This double-blind randomized controlled trial involved 38 habitual blood donors with prediabetes. Prediabetes comprised borderline glycemia measured by any of the following: fasting glucose, 100 to 125 mg/dL; HbA1c, 5.7 to 6.4%; or 2-hour glucose, 140 to 199 mg/dL after 2 hours of ingesting 75 g of glucose (OGTT). Participants were randomized to a blood donation group (450 mL; DON; n = 20) or a simulated donation group (6 mL; SIM; n = 18). Measurements were collected before and 2 weeks after the intervention and included fasting ferritin, insulin resistance (HOMA-IR), liver enzymes, and lipid profile. During the OGTT, blood glucose, insulin, free fatty acids, and rates of carbohydrate oxidation were assessed.

Ferritin decreased significantly only in DON (-25.4 μg mL^-1; P < .001). DON also lowered fasting insulin (-1.48 μIU mL^-1; P = .048), HOMA-IR (-0.525; P = .030), alanine aminotransferase (-4.25 IU L^-1; P = .005), and early-phase OGTT glucose (0-45 min; P = .003). In contrast, fasting lipid profile, adipose tissue insulin resistance, or carbohydrate oxidation rates during the OGTT did not differ between groups.

A single blood donation reduces iron stores and is associated with improvements in surrogate markers of hepatic insulin resistance, decreases markers of liver damage, and enhances early-phase glucose tolerance in overweight individuals with prediabetes. The data suggest that blood donation could help improve short-term glycemic control in people with prediabetes.