Testing for Diabetes
Whether you suspect you have diabetes, are newly diagnosed, or have been managing your diabetes for years, it is essential to know your blood sugar numbers. There are new tests and new equipment on the market to help you keep track. As a specialized provider of diabetes care, Mount Sinai Health System can help you navigate this ever-changing world so you can manage your disease without it managing you.
Types of Tests
We can tell if you have diabetes by measuring your blood sugar levels. We use several tests:
Fasting blood glucose is the most reliable test. We usually perform this test in the morning before you have eaten anything or after an eight-hour fast. Blood glucose is measured in milligrams per deciliter (mg/dL). To confirm a diagnosis, we perform the test twice. Possible scores are:
- Normal = 99 mg/dL and below
- Prediabetes = 100 to 125 mg/dL
- Diabetes = 126 mg/dL and above
Oral glucose tolerance test can help us identify diabetes, prediabetes, and gestational diabetes. You must fast for at least eight hours before taking the test. We measure your blood glucose level immediately before and two hours after you drink a liquid that contains a small amount of glucose.
- Normal = 139 mg/dL and below
- Prediabetes = 140 to 199 mg/dL
- Diabetes = 200 mg/dL and above
For a diagnosis of gestational diabetes, values are above normal at two or more of the times: 95 mg/dl or higher after fasting; 180 mg/dl or higher at one hour; 155 mg/dl or higher at two hours; or 140 mg/dl or higher at three hours.
Random plasma glucose test enables us to test your blood glucose at any time of the day without requiring you to fast. You likely have diabetes if your glucose level is 200 mg/dL or more and you have any of the following symptoms:
- Increased urination
- Increased thirst
- Unexplained feelings of hunger
- Unexplained weight loss
- Blurry eyesight
- Frequent vaginal yeast infections
- Sores that do not heal
To confirm a diagnosis of diabetes, we will retest your blood sugar levels with the fasting blood glucose test or the oral glucose tolerance test.
There are many types of blood glucose meters available. Each model uses a specific type of strip, so be certain you purchase strips that are made specifically for your meter.
Glucose meters are constantly changing and upgrading. Many people with diabetes get a new meter about once a year to have the latest technology. Your doctor or diabetes educator can help determine which meter is best for you. Once you select a glucose meter, you should read the instructions carefully and follow them closely.
Choosing a Meter
There are many factors to consider when choosing a meter that is right for you:
- Ease of use (this is especially important for small children, elderly people, or those with physical or mental limitations)
- Cost of test strips
- Cost and availability of batteries
- Size and portability
- Speed of registering a reading
- Readability (meters are available for the visually impaired or color blind)
- Whether a doctor can check the meter's memory
- Whether the meter's memory can be downloaded onto a computer
- Insurance plan coverage
- Whether the manufacturer has a 24-hour toll-free phone number to call with questions or problems
Checking Glucose Levels
Elevated blood glucose (sugar) levels increase the risk of complications from diabetes, so you should check your glucose levels regularly. How often you need to check your glucose levels depends on your type of diabetes and individual circumstances, so talk to your doctor or diabetes educator to work out a testing schedule that is right for you.
You may want to test your glucose levels more often than required by your schedule if you:
- Change your eating habits or stray from your meal plan and are unsure of how the changes will effect your glucose levels
- Are about to exercise and want to know if you should eat something to bring your glucose levels up or need to exercise more to bring your glucose levels down
- Are sick
- Are taking a medication that may affect glucose levels or your ability to recognize the warning signs of low glucose (hypoglycemia)
- Change your diet, exercise routine, or insulin plan
- Lose or gain weight
- Have glucose levels outside your recommended range
- Have had unstable glucose levels and are about to drive a car, to be certain you are not at risk for hypoglycemia. Losing consciousness while driving could put your life and the lives of others at risk.