The expressions of the type XVIII collagen, syndecan-1 (SDC1), and CD44, which represent HSPGs, HS, and heparanase, respectively, decreased in islets from both young T2DM-prone db/db mice and Akita Ins2WT/C96Y mice, in association with elevated endoplasmic reticulum stress markers [16]. Here, SDC1 is linked to type 2 diabetes mellitus.