Is 5.2 mmol fasting blood sugar normal, or is it nearing prediabetes? i am a 24 year-old female?

It is normal and does not indicate diabetes of even pre-diabetes. For healthy diet: http://www.choosemyplate.gov/., exercise 30 minutes/day, drink enough water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. Get HPV vaccine. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines

Pre-diabetes best tested with OGTT. Discuss with your Dr. Review your family tree for diabetes.