There can be two reasons for your tingling sensations on your face.
1... Diabetic neuropathy
due to uncontrolled diabetes
2.. Lack of VIT B12 due to consumption of metformin
and partly to dietary insufficiency which takes place more,if you happen to be a vegetarian or a vegan.
Consult a diabetologist
,get properly investigated and then take proper treatment.
Prompt control of blood sugar is very important for alleviation of your symptoms.
Take all dietary precautions.
Do regular exercises.
Take VIT B 12 either orally or it would be better if you take few injectable VIT B 12 under the guidance of your doctor.