The proportion of islet area comprised of somatostatin-immunopositive cells also increased, from 6.2±1.1% of the islet area in the 4 wk old group to 23.2±1.1% (p<0.01) in the diabetic group with delta-cell mass increasing concomitantly as diabetes progressed (0.03±0.01 mg in 4 wk and 0.06±0.01 mg in 20 wk p<0.05). Here, SST is linked to diabetes mellitus.