Insulin and Insulin Pulses During Fasting

This study is investigating how the body produces insulin in pulses (bursts) during fasting, and how glucose (blood sugar) metabolism changes in people who have early signs of blood sugar problems — specifically prediabetes or elevated fasting glucose — but do not yet have full diabetes. **You may be eligible if...** - You have normal or slightly elevated fasting blood sugar (prediabetes range) - You have normal or mildly impaired glucose tolerance **You may NOT be eligible if...** - Your HbA1c (a measure of average blood sugar) is above 6.5% (which would indicate diabetes) - Your BMI is 35 or above - You are taking any blood sugar-lowering medication (including metformin) - You are pregnant - You have had upper abdominal surgery (like gastric banding) - You have an active illness or cancer - You have a blood disorder (low hematocrit) Talk to your doctor to see if this trial is right for you.