you should read the package insert with sinemet--the section called laboratory tests. i am not a medical person but i do have pd and last summer became diabetic. luckily i was able to give up all sugar--meaning sodas, juices, desserts--and have things under control now without meds. i do personally believe however that the sinemet affects glucose readings. good luck n.s. also you can call the drug manufacturer for info. i've found them helpful though in the end they always recommend discussing subject with your m.d. or having him/her call the pharmaceutical firm.