Question About A1C. I Am African American. I Am 5'10"

Question about A1C. I am African American. I am 5'10" and 161 lbs. I am 61 years old. I've played tennis all my life since 6yrs old. I work out consistently. My A1C was 5.4. After 3 months it went to 5.8. After another 3 months it went back to 5.4 (tested on October 10, 2016). Diabetes does not run in my family. All my other blood work got excellent marks. At what point am I considered diabetic?