There is a lack of research in this area, as far as we can tell carbohydrates don't not affect Parkinson’s drugs.
We did a bit of digging and there is some evidence that a high carbohydrate diet may decrease the absorption of a type of drug that relaxes the muscles of the airways. However there is no link between the effectiveness of Parkinson’s medication and eating carbohydrate.
Tablets should always be taken as advised by your doctor, some tablets should be taken with food. You may be recommended to eat some carbohydrate rich food – like a biscuit of cracker – before taking medication as it can help protect the stomach lining, protein is known affect absorption of some Parkinson’s medications.