Top frequently asked questions about diabetes and blood sugar. Browse our site to see many more diabetes questions and answers.

Q: What is a normal blood sugar level?

A: A person without diabetes will have an A1C test below 5.7%, a fasting blood glucose test less than 100 mg/dl, and a glucose tolerance test of 140 mg/dl or below. Learn more about diabetes test results.


Q: What is a normal blood sugar 1 hour after eating?

A:  The highest peak blood sugar levels generally occur 1 hour after a meal if carbohydrates were eaten. At 2 hours after a meal, protein begins to break down into blood sugar which could again increase blood sugar. Generally, over the course of a day, your blood sugar should not go over 140, even after eating a large meal. Ideally it would not go over 120 two hours after eating. This goal should be discussed with a medical provider because some people may require a higher goal in order to avoid hypoglycemia (low blood sugar).
Learn more about what to eat when you have diabetes.

Q: Do I have pre-diabetes if my fasting blood sugar is 102?

A: You are considered to have pre-diabetes when either
1) your A1C test is between 5.7% and 6.4%
2) your fasting blood glucose is between 100 and 125 mg/dl
3) your oral glucose tolerance test is between 140 and 199 mg/dl.
Learn more about prediabetes.


Q: How do I test for diabetes?

A: You are considered to have diabetes when either
1) your A1C test is 6.5% or greater
2) your fasting blood glucose is 126 mg/dl or greater
3) your oral glucose tolerance test is 200 mg/dl or greater
Learn more about diabetes test results.

Q: Why is my blood sugar high in the morning?

A: This early morning rise in glucose, known as the “dawn phenomenon” is normal and happens when our bodies produce a surge of hormones to help us wake up. During the day, activity tends to keep sugars under control if following a healthy, active lifestyle. If using insulin, it may help to adjust your nighttime dosage. Learn more about reducing stress to improve your blood sugar.


Q: What is the A1C test?

A: The A1C (also called HbA1c) is a blood test shows how blood sugar levels were controlled over the previous two to three months. It should be done by your doctor at least twice a year. Aim for a level below 6.5. 


Q: Do I need to fast before an A1C test?

A:  No, fasting is not required for an A1C because the test measures your average blood glucose levels over the past three months.

Q: How long should I fast before a fasting glucose blood test?

A: At least 10 hours gives your body a chance to digest all food in your system to more readily determine what your true fasting blood sugar is. Carbs, proteins and fats all digest at a different rate and a larger meal will take longer to digest. A fasting blood sugar of 126 repeated twice is a diagnosis of diabetes.

Q: Can I drink black coffee before a fasting glucose blood test?

A: No, do not drink coffee, even if it is black. You can only drink plain water so do not drink coffee, tea, or anything else before a fasting blood test, even if it is diet/unsweetened.


Q: Can stress increase blood sugar levels?

A: Stress can elevate blood sugar, and if you are already requiring insulin when you are otherwise unstressed, you may need more at these times. Be sure to monitor yourself in all situations as closely as you can. Learn more about reducing stress to improve your blood sugar control.


Q: Can being sick increase blood sugar?

A: Illness can lead to an increase in blood sugar levels. The most important step to take during illness is to make sure that blood sugar levels are stable to prevent a small problem like a cold or the flu from causing greater problems. Learn more about diabetes and illness.


Q: What are the best foods to lower my blood sugar?

A: There is no one answer to your question; your meal program needs to be individualized to meet your needs. Testing your glucose at different times during the day will let you know how your foods are affecting your levels. Eat high fiber foods, drink lots of water, and focus on eating veggies, legumes, and fish.

Q: When is the best time to test my blood sugar?

Most people with well-controlled diabetes who are not taking any medications need to have their blood sugar checked only 2 - 3 times a week. Monitoring 2 - 4 times a day is necessary for most individuals with diabetes in order to track the changes that may occur. People with diabetes who are ill, have more than two insulin shots a day, or are pregnant, may need to check blood sugar even more often. The best times to do this are before breakfast, lunch, and dinner, at bedtime, and 1 - 2 hours after meals. Learn more about monitoring your blood sugar.


Q: Why is my blood sugar higher after exercise?

A: Wait an hour after you exercise and see if you get the same results. Exercise is a stressor, so blood sugar will be higher immediately after your session.

Q: Does hot or cold weather affect blood sugar levels?

A: High heat can lead to dehydration, which in turn can cause high blood sugars. It takes 6 molecules of water to move one molecule of sugar from the blood stream, so the higher the sugar, the more water you need to drink. Extreme hot or cold temperatures can cause changes in the vascular system that can affect blood sugar and cause reactions.

Information on the "Question and Answer" pages should not be relied on for medical or technical advice. Always consult your healthcare team. Diabetes Action and Jane DeVane cannot be responsible for errors or wrongful use of the information available on this website. The information provided on this site is designed to support, not replace, the relationship that exists between a patient/site visitor and his/her physician/medical team.