Sudafed and blood sugars

So, what does Sudafed do to your numbers? The doctor wanted me to start taking Sudafed. I have been taking Zyrtec, which hasn't affected them, but Sudafed info says it might affect blood sugar levels. If it does affect it, how long does it take, and does it raise or lower?

Sudafeds main ingredient is Pseudoephedrine and may increase blood sugar. Check blood sugar levels closely and ask your doctor before adjusting the dose of your diabetes medicine.