Your friend should be taking insulin regularly without missing a dose. The levels up to 100 are considered normal, and levels between 100 and 126 are considered pre-diabetes. High sugar levels can be devastating on the body which can cause complications such as heart disease and stroke, blindness, hypertension, diabetic neuropathy, nerve damage, depression, complications with feet, kidney disease and limb amputation. So tell him to keep his sugars under good control with diet, exercise and insulin.