My type 2 dm friend's metformin is no longer working to manage his blood glucose. he is normal, weight but stressed. does stress affect glucose levels?

Yes: Indeed stress adds insult to injury.

Yes!: Yes, both physical stress and emotional stress can effect diabetes.

Stress: Severe stress to the point of agitation secretes Adrenalin and can elevate the blood sugar. If his diabetes is out of control, he should call his physician who will review his diet and probably add to his antidiabetic medication as well as address the stress issue.