GPC1 and diabetic cardiomyopathy: Membrane proteoglycans Gpc3 and Sdc1 have not yet been demonstrated to play a role in the development of diabetic cardiomyopathy, however, increased expression of the heparan sulfate proteoglycans Gpc1 and Sdc4 has been shown to lead to diastolic dysfunction in streptozotocin-induced diabetic rats [64].