Yes and no.
In monotremes, which includes the platypus, there are mammary glands but no teats. When producing the milk, the mother excretes milk out of pores in the skin and the young platypuses lick the milk off the abdomen. The mother has grooves specifically designed to keep milk that is excreted out.
These glands from which the milk is secreted are modified sweat glands on the platypus's abdomen. In all mammals, the mammary glands are really little more than modified sweat glands, but it's the the absence of nipples which is more obvious in platypuses.
Interestingly, the male platypus's venom gland is also a modified sweat gland.