I had the exact same thing going on with me this past October. I started feeling bad in September, and because I had gestational diabetes when I was pregnant 8 years ago, I've always been concerned about getting type 2 diabetes. I have my own blood sugar monitor, so I started checking my fasting sugar & also sugar during the day. My fasting sugar was always high at 125 - 135. However, during the day my sugars were fine.
Normal fasting blood sugar should be under 100. Anything between 100 and 125 is impaired fasting glucose and and anything 125 or above is consistent with type 2 diabetes if other symptoms are present. Here's the link from Mayo Clinic showing this.
(http://www.mayoclinic.com/health/blood-sugar/SA00102)
I knew something was wrong because I was experiencing tiredness, stomach problems, flushness, confusion, inability to concentrate, irritable, inability to lose weight etc. I went to my doctor and told her that I was sure my sugars were messed up and requested the 2 hours glucose test along with an insulin check. Whereas my blood sugar returned to normal after the 2 hours, my insulin was sky high. It was 151 and normal is under 10. My official diagnosis is "insulin resistance" which is a step towards diabetes.
I immediately changed my diet to low-carb and started exercising. I was also prescribed Metformin and started taking that. Within two months, I'd lost 16 pounds and my insulin was now down to 17, almost normal! My morning fasting blood sugar readings now vary from 85 to 105. All my other symptoms cleared up too.
Left untreated, this insulin resistance will eventually lead to high blood sugar readings during the day, and can eventually lead to full blown type 2 diabetes if not treated.
Are you having any other symptoms other than the high fasting blood glucose? I would suggest asking your doctor for a 2 or 3 hours glucose test that includes an insulin measurement.
Hope that helps!
The reason they take fasting sugars is because when we sleep at night due to the inactivity our levels will actually increase even though we have not eaten all night. And our metobolism slows at night so sugars will actually increase. If you have a very active schedule by day I would say this is quite normal. Bear in mind that 120-135 is not HIGH but it is just on the high side of normal. Hope that helps some.
I would also like to add that my A1C is totally normal. I just don't understand why I am getting the high fasting blood sugars.