Hi. My fasting bg 96 mg/l, insuline 2, 42 miu/l, hba1c% 3, 85%, c-peptide 0, 71 ng/ml (my lab`s ref range for c-pep: 0, 78-5, 19).Is my c-peptide too low? Thx

Normal. All of these results are normal. The c-peptide is of limited value. It can help in the diagnosis of type 1 diabetes if the blood sugar is high. Your say that you have type 2 diabetes and are taking metformin/vildagliptin but have a bmi of 15.9. I would seriously question the diagnosis of type 2 diabetes, and would get an opinion from an endocrinologist.