Abstract
The response of plasma glucagon to insulin-induced hypoglycemia in diabetics whose fasting blood sugars (FBS) were normalized by conventional therapy was investigated. The diabetic subjects were classified as follows. Group Da consisted of 10 patients whose FBS levels were up to 100 mg/dl, while group Db consisted of 9 patients whose FBS levels were more than 100 mg/dl but less than 140 mg/dl The control group (N) consisted of 12 non-obese, healthy subjects.
The blood ugar, plasma glucagon (IRG), growth hormone (HGH), and adenosine 3, 51-monophosphate (cAMP) were measured before and after intravenous injection of MC ctrapid insulin at a dose of 0.05 U/kg in group N and 0.05 U/kg or 0.1 U/kg in groups Da and Db. The FBS levels in groups N, Da and Db were 85±2 M±SE, 88±3 and 114±3 mg/dl, respectively. The minimal blood sugar levels after insulin injection in groups N, Da and Db were 37±2, 39±3 and 43±mg/dl, respectively. No significant differences in the responses of plasma HGH and cAMP were observed among the three groups. The plasma IRG levels before insulin injection in groups N, Da and Db were 108±27, 117±22 and 117±26 pg/ml, respectively. The maximal AIRG evels in groups N, Da and Db were 107±22, 69±15 and 22±14 pg/ml, respectively. Although the maximal AIRG levels in groups N and Da were not significantly different, the maximal AIRG level in group Db was significantly lower than that in group N. The incremental areas of plasma IRG for 120 min in groups N, Da nd Db were 4128±823, 2967±523 and -591±1254 pg. min/ml, respectively. There was no significant difference between the incremental reas of plasma IRG in groups N and Da, but the incremental area of plasma IRG in group Db was significantly lower than in group N.
In conclusion, it is suggested that the responsiveness of pancreatic A-cell function can be normalized in diabetics, if the diabetes mellitus can be well controlled, and that abnormality of pancreatic A-cell function in diabetes mellitus may result, secondarily, from shortage of insulin action.
