Spontaneously diabetic C57BL/6J obob and C57BL/Ks dbdb mice have been shown to have significantly decreased immunoassayable pancreatic somatostatin concentrations compared to lean littermate controls at 11-12 weeks: obob 1.06+/-0.15 pg/mug protein (n=10) vs control 1.94+/-0.-6 pg/mug protein (n=10) (mean +/- SE; p less than 0.005); dbdb 0.7+/-0.2 pg/mug protein (n=8) vs control 1.5+/-0.2 pg/mug protein (n=8) (mean +/- SE; p less than 0.005). An inverse relationship between circulating insulin levels and pancreatic SRIF concentration is suggested.