a friend of mine wanted to check for diabetes,so he went ahead with a test called the OGTT (Oral Glucose Tolerance Test),where after drawing blood for the fasting morning sample,75 gms of glucose mixed in 300 ml of water is administered and either half hourly or hourly blood samples are tested for glucose values.
His fasting was 103mgs,first hour reading was 140,second hour reading fell to 64 and then they did what is called an extended OGTT, where a third hour sample is tested.It was 44mgs and he started feeling dizzy.
This scenario as the Endocrinologist diagnosed is called "REACTIVE HYPOGLYCEMIA" where inappropriately high insulin is released from the pancreatic beta cells to a given glucose load,causing dramatic falls in blood glucose levels.
This kind of picture is like the final burst of flame from a flickering candle before it extinguishes.The beta cells are fast getting exhausted and Insulinopenia(low insulin levels) ensues and the person becomes a frank diabetic!
You did not mention whether your fasting sugar was tested in a lab or with a glucometer,because glucometers are not meant for diagnosis(there is a thread in this forum on glucometer accuracy).
My suggestion to you would be to go in for a OGTT,first thing in the morning in a truly fasting state,that is you must have a normal dinner without any sweets in it, at least 10 hours before the first sample is drawn.Have your dinner at 8 p.m and see that your blood is drawn at 8 a.m the next day morning!
Then we'll know what is happening in your system.My best wishes stay with you!