Glucose tolerance, plasma insulin and C-peptide during chloroquine treatment of rheumatoid arthritis

Since and adverse effect of chloroquine (Cq) on the specific functions of the pancreatic beta-cell has been recently documented in animals, it was of interest to study if a similar effect could be demonstrated during Cq treatment in homo. The effect of Cq on glucose tolerance and insulin secretion was studied in 10 patients with rheumatoid arthritis (RA) over a 3-month period. Fasting plasma levels of glucose, insulin, C-peptide and glucosylated haemoglobin (HbA1c) were checked before starting treatment, after 3 months' Cq treatment and 3 months after withdrawal of treatment. At the same intervals oral glucose tolerance tests (OGTT) were performed. No significant change in any of these parameters was found during treatment with Cq. In patients with a normal OGTT, Cq inhibition of insulin synthesis and/or secretion cannot be demonstrated, as measured by a decreased plasma insulin an C-peptide response to oral glucose load.