Yes, a fasting blood sugar of 155 is too high, and may indicate that she has health problems beyond her obesity ... Insulin resistance and Type 2 diabetes are becoming more and more common in children, unfortunately. Or she may be taking medications ... cortisone for asthma or allergies will affect weight gain and higher blood sugars. Etc ....

I would focus any "alarm" on the blood sugar reading, and encourage this young lady's guardian to seek medical attention. At this point, without knowing the diagnosis, it wouldn't be helpful to recommend a "diet" although suggesting that she cut out all sugar, sweets and processed starches might be well-received. Perhaps finding out that there's health problems beyond just the weight problem mihgt convince the guardian to make some changes

Doreen