Abstract
The aim of this study was to determine whether the unresponsiveness of diabetic A cell to glucose was etiologically connected with the disturbamce of B cell functions or a primary lesion independent of the B cell functions. The relationship between the glucose responsiveness of A and B cells was ilvestigated in 53 diabetics. Responses of plasma glucagon immunoreactivity (ΣΔGI) to oral glucose (OGTT) and intravenous injection of insulin (ITT) were determined as the A cell function. The B cell responsiveness to glucose was assessed by ΣΔIRI or ΣΔC-peptide immunoreactivity (CPR) during OGTT. ΣΔGI was inversely correlated with ΣΔCPR during OGTT (r= -0.36, P=0.05) in 29 diabetics. ΣGI in ITT was well correlated with the respective patient's ΣΔCPR in OGTT (r=0.79, P<0.001), but ΣGI in arginine test (AT) was not (r=0) in 18 insulin-treated diabetics. The A and B cell responses to ITT, AT and OGTT were measured before and 1.5 month (mean) after commencement of treatment in 6 diabetics when their FBS levels fell to nomal levels. ΣΔIRI in OGTT was raised significantly and augmented plasma GI response to AT was normalized after the period of treatment. In addition, af tertreatment, the A cell response to ITT tended to be increased.
It is concluded that the glucose responsiveness of A cells seems to be connected with B cell activity and disturbances of the A cell functions are most likely secorldary.
