The effect of insulin deprivation on fasting levels of 5000 dalton gastric inhibitory polypeptide in type 1 (insulin-dependent) diabetics.

To investigate whether metabolic decompensation has an effect on gastric inhibitory polypeptide (GIP), 8 fasting male type 1 diabetics were deprived of insulin for 12 h. An overnight insulin infusion aiming at normoglycaemia was stopped at 08.00 h. During the following 12 h blood glucose increased from 7.0 +/- 0.4 to 14.9 +/- 1.0 mmol/l, P less than 0.01, 3-hydroxy-butyrate from 0.18 +/- 0.07 to 4.00 +/- 0.74 nmol/1, P less than 0.01, and immunoreactive GIP (IR-GIP) from 16.7 +/- 2.6 to 21.9 +/- 2.9 pmol/1, P less than 0.05. The antiserum employed, R65, only measures 5000 dalton IR-GIP. The final IR-GIP concentrations were not significantly different from fasting IR-GIP concentrations in 13 normal male subjects (17.4 +/- 1.5 pmol/1). Short term insulin deprivation therefore is associated with a slight increase in fasting IR-GIP concentrations. Whether this modest increase in IR-GIP significantly enhances insulin secretion is unknown.