High glucose above 180-230 and low A1c of 5.8

I always been told that I need to have not eaten or drank (except water) for 8 hours before you take your blood sugar levels.

Next time you go to your doctor, take your Glucose level at home. When you are at the doctor's office take it again. If they do not closely match then you may have a bad meter.

I am somewhat like you. My Glucose levers with 8 hours of no eating are in the range of 100-120 consistently (not as high as you). Even at the doctor's office. My A1Cs are usually in the 5.5-5.8 range for several years. My doctor thinks the higher glucose is normal for me and with my A1C he is not overly concerned. My last 2 A1Cs were 5.3 which even surprised my doctor. And I have no idea why that fluxurated.

I use a Medtronic 780G insulin pump and a 630 G inulin user for 6 + years. My A1C is between 5.3 - 5.5.
I am up at 1 AM due to chronic nerve pain, diabetic autonimic peripheral polyneuropathy and Cervical spondylosis & Lumbar spondylosis . If I have to go for a fasting blood sugar test. I pick the first test at 6:15 am. My glucose is at 90 and slowly drop to 70 before 5pm . My pump works in a 4 hour My Endrocrinologist doctor know that I have to eat a gluclose tablet or get to get my reading up to 110. I do no drive a car . I have to walk 4 blocks to catch a public bus. When My BLOOD SUGAR READING was 300 and above , my A1c was 7.0 to 7.5 . this was also a fasting test. My body refused any syringe shot of Humalog. I was taking 4-5 shots a day . .my problem stopped when I transferred to the insulin pump . I am a type 2 .I have small fiber neuropathy that lead to me having to get a pacemaker, low Bradycardia in the med 30's , heart beating every 7 seconds.

Type 2. Had the same issue. Turns out my little snacks during day was keeping glucose up and A1C was down. It was ME!