oral D-ribose (5 g/dose) for 6 weeks

D-ribose (0.5 mM) was added to foetal calf serum or human urine at 37 °C, and aliquots were collected and used for measurement of D-ribose at different time intervals (0, 2, 4, 6, 8, 24, 36, 48, and 72 h). Haemoglobin (10 mg/ml) was incubated with different concentrations of D-ribose (0, 1, 20, 50, 100, and 200 mM) for 5 days, and aliquots were collected and used for the detection of HbA1c each day. Haemoglobin (10 mg/ml) was incubated with 0.2 mM D-ribose or 7 mM D-glucose (0, 6, 12, 24, 36, 48, 72, and 96 h), and aliquots were collected and used for detection of HbA1c at each interval. HbA1c was determined with an ELISA kit for human HbA1c. D-ribose reacted with the N-terminal valinyl residues of Hb, thus producing significantly higher HbA1c levels (P < 0.001) than D-glucose after three days of incubation with 0.1 M D-ribose or 0.1 M D-glucose. This result demonstrated that both D-ribose and D-glucose glycate Hb and produce HbA1c.