Glycosylated haemoglobin in rheumatoid arthritis.

Shortened red cell survival has a role in the anaemia of rheumatoid arthritis (RA), but direct measurement of it is difficult. Glycosylated haemoglobin (HbA1) provides an index of red cell life span in normoglycaemic patients, because glycosylation depends on both the concentration of blood glucose and the duration of erythrocyte survival. HbA1 was significantly lower in 30 patients with RA (5.6 +/- 0.7%, mean +/- SD) than in 15 healthy controls (7.3 +/- 0.7%) and 14 patients with osteoarthritis (7.4 +/- 0.7%, p less than 0.001). HbA1 was depressed less in active RA than during remission, which is consistent with diminished red cell production in active RA. These data on HbA1 confirm that shortened red cell survival is common in RA, and point to diminished red cell production in active disease. Determination of HbA1 should prove to be of clinical value in the assessment of normoglycaemic patients with RA but is an inadequate index of glucose homoeostasis in diabetics with RA.