I am an avid athlete and have exercised my entire life. It was actually my career until I retired a few years ago. I am not overweight and have maintained my current weight for many years.; I am 5’4″ 130 pounds. Over the last few years, the blood work prior to my annual physical has shown a slightly elevated fasting blood glucose level, 102 to 112 mg/dl [5.6 to 6.2 mmol/L], that highest reading being my latest test. Just one week earlier, was 102 mg/dl [5.6 mmol/L]. The doctor wanted to redo the test because of an elevated potassium level. The second blood test showed a better result for the potassium but the blood glucose was a little higher, as was and the BUN. The first test was done about 2 hours after a very intense workout and I believe some of the test results were effected by that. The second test, however, was on a rest day for me, but the blood glucose levels were elevated even more. There is no history of diabetes in my family at all. I eat a healthy diet and avoid sweets. I also have a strangely high average heart rate for someone that works out as intensely as I do. Don’t know if any of that is related. I’m not sure what to think at this point. Do I have prediabetes? Should other tests be run to narrow this down? I feel great, with no symptoms that I am aware of related to the onset of diabetes.

It looks like you do not have diabetes from the information submitted. Keep up the good work with lifestyle modifications; from the numbers given, you have “impaired fasting glucose” (i.e one of the three forms of “prediabetes”) and, if your random reading were also in non-diabetic range your chance of getting diabetes would be slim. If you need a definitive answer, you should undergo a formal, diagnostic, 2 hour (75-gram glucose) oral glucose tolerance test, which would need to be performed in a certified laboratory, after preparation consistent with the way that test was standardized.

This is an abbreviated description:
To perform the glucose tolerance test, the patient should be instructed to eat a normal carbohydrate diet of at least 150 grams of carbohydrates for at least three days prior to the test. On the day of the test typically a patient must arrive in a fasting state.
A fasting sample is taken either by phlebotomy or intravenous access to establish a baseline glucose level. Then, the patient will drink the glucose (75 grams). The amount is dosed by weight in pediatric patients at 1.75 g/kg of body weight, while the maximum dose for all patients is 75 grams.
Patients are asked to fast throughout the test except for drinking the glucose. Samples are then taken at various timepoints ending at either 60 or 120 minutes post consumption of glucose. Throughout the test, patients should remain inactive, and excess hydration with water should be discouraged as these can impact the results of the test.