I am also diabetic and have been for 15 years. Over the past two weeks or so I have also noticed quite severe sweating when I eat.
I have not seen my gp yet but did discover this article on the net which I found interesting hope it helps.
Definition of gustatory sweating
gustatory sweating: sweating on the forehead, face, scalp, and neck occurring soon after ingesting food. Some gustatory sweating is normal after eating hot, spicy foods. Otherwise, gustatory sweating is most commonly a result of damage to a nerve that goes to the parotid gland, the large salivary gland in the cheek. In this setting, referred to as frey syndrome, the sweating is usually on one side of the head. Gustatory sweating is also a rare complication of diabetes mellitus. In this case sweating may occur on both sides of the head, with mild or substantial severity.
This distressing problem can be difficult to treat. Treatments used include oxybutynin chloride, propantheline bromide, and clonidine (brand name: catapres). Recently, some success has been reported using topical applications of glycopyrrolate: the lotion was applied to the skin of the forehead and face, sparing the eyes and mouth. See also frey syndrome, diabes.