Gastric inhibitory polypeptide (GIP) responses in type 2 diabetes using three different antibodies.
Contradictory reports of gastric inhibitory polypeptide (GIP) responses in diabetes have been published by different workers using different radioimmunoassay systems. The present study was undertaken to assess GIP responses in type 2 diabetes using three antibodies (S100, GP01 and GP24). Seven untreated diabetics and seven healthy control subjects had a standard 50 g oral glucose tolerance test. An alcohol extract of plasma of each sample was assayed using these three different antibodies. Using S100, GIP responses in the diabetic group were significantly lower at 30' (P<0.025) and at 120' (P<0.01) and the integrated incremental GIP responses also were significantly lower in the diabetic group (P< 0.025). Using GP01, GIP responses in the diabetic group were significantly lower only 120' (P<0.05) but there was no significant difference in the integrated incremental GIP responses. Using GP24, there was no significant difference between the diabetic and control groups at any time intervals or in the integrated incremental responses. However, three to sixfold higher levels of GIP were recorded when using GP24 as compared with the other two antibody systems which gave similar absolute values. Structurally abnormal variable cross-reacting 5000 dalton (5 kDa) and 8 kDa GIP forms or still unidentified structurally GIP related peptides associated with type 2 diabetes might be responsible for these conflicting results.
Alam
M J
MJ
Department of Medical Biochemistry, College of Medicine, King Saud University, Riyadh, and Department of Medicine, Queen's University of Belfast, U.K.
Buchanan
K D
KD