NO CORRELATION BETWEEN INSULIN AND ISLET AMYLOID POLYPEPTIDE AFTER STIMULATION WITH GLUCAGON-LIKE PEPTIDE-1 IN TYPE-2 DIABETES

Objectives: To examine whether glucagon-like peptide I (GLP-1), which has been suggested as a new therapeutic agent in type 2 diabetes, affe cts circulating islet amyloid polypeptide (IAPP), a B-cell peptide of potential importance for diabetes pathophysiology. Design: GLP-1 was a dministered in a buccal tablet (400 mu g) to seven healthy subjects an d nine subjects with type 2 diabetes. Serum IAPP and insulin levels we re measured before and after GLP-1 administration. Results: In the fas ting state, serum IAPP was 4.1 +/- 0.3 pmol/l in the controls vs 9.8 /- 0.9 pmol/l in the subjects with type 2 diabetes (P < 0.001). IAPP c orrelated with insulin only in controls (r=0.74, P=0.002) but not in t ype 2 diabetes (r=0.26, NS). At 15 min after GLP-1, circulating IAPP i ncreased to 6.0+/-0,5 pmol/l in controls (P=0.009) and to 13.8+/-1.2 p mol/l in type 2 diabetes (P=0.021). In both groups, serum insulin incr eased and blood glucose decreased compared with placebo. In controls s erum IAPP increased in parallel with insulin (r=0.79, P=0.032), wherea s in type 2 diabetes the increase in IAPP did not correlate with the i ncrease in insulin. Conclusion: Type 2 diabetes is associated with ele vated circulating IAPP; GLP-1 stimulates IAPP secretion both in health y human subjects and in type 2 diabetes; IAPP secretion correlates wit h insulin secretion only in healthy subjects and not in type 2 diabete s.