• Diagnosis of Type 1 Diabetes

    The doctor will ask about your symptoms and medical and family history. A physical exam will be done. The doctor will also do a few tests. There are 4 main tests used to diagnose diabetes. The American Diabetes Association (ADA) list the following test as options for diagnosis:

    Symptoms and Results of Random Plasma Glucose Test

    Symptoms typical of diabetes include excessive thirst and hunger, frequent urination, and weight loss. Your doctor will make the diagnosis based on your symptoms and the results of the random plasma glucose test. This test is taken any time of day, without regard to when you have last eaten. A sample of your blood will be taken. The blood glucose level will be measured. A measure of 200 (mg/dl) [11.1 mmol/L] or higher indicates the presence of diabetes.

    Two-hour Glucose Tolerance Test

    This starts with a 3-day intake of a diet consisting of at least 150 grams of carbohydrates. You will then be asked to fast overnight (between 8-16 hours). The test is generally done in the morning, in your doctor's office.
    A sample of your blood will be obtained to measure blood sugar. Then, you will consume a drink that contains 75 grams of glucose dissolved in water. Two hours later, another blood sample will be obtained to measure blood sugar. If you have diabetes, your blood sugar level will rise higher than normal and remain high for a much longer time than is normal. A measure of 200 mg/dl (7 mmol/L) or above at 2 hours is considered a positive test.

    Hemoglobin A1c (HbA1c)

    The HbA1c test is a good indicator of your average blood sugar levels over the previous 2-4 months. This test usually does not require any dietary restrictions. A sample of your blood will be taken. If your HBA1c level is 6.5% or higher, this indicates a diagnosis of diabetes.

    Fasting Plasma Glucose Test

    You will need to eat nothing for at least eight hours before the test. A sample of your blood will be taken. The blood glucose level will be measured. A measure of 126 milligrams per deciliter (mg/dl) (7 millimole per liter of blood [mmol/L]) or higher on 2 separate occasions indicates a diagnosis of diabetes.

    Other Tests

    After the diagnosis of diabetes is confirmed, your doctor will most likely order the following tests:
    • Urine microalbumin—to see if there is any damage to your kidneys by measuring protein in your urine
    • Thyroid function tests
    • Blood lipids (cholesterol) levels (total low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol, triglycerides)
    • Kidney function tests including serum creatinine, blood urea nitrogen (BUN), and potassium
    Less commonly ordered tests may include:
    • Glutamic acid decarboxylase (GAD) antibodies
    • Plasma insulin levels
    • Islet cell antibodies
    • Plasma C-peptide
    • Insulin antibodies


    American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010;33(Suppl 1):S62-S69.

    Arnold JG, McGowan HJ. Delay in diagnosis of diabetes mellitus due to inaccurate use of hemoglobin A1C levels. J Am Board Fam Med. 2007;20(1):93-96.

    Causes of diabetes. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: http://www.niddk.nih.gov/health-information/health-topics/Diabetes/causes-diabetes/Pages/index.aspx. Accessed December 31, 2012.

    Diabetes mellitus type 1. EBSCO DynaMed website. Available at: EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 28, 2012. Accessed December 31, 2012.

    Type 1 diabetes. American Diabetes Association website. Available at: http://www.diabetes.org/diabetes-basics/type-1/?loc=DropDownDB-type1. Accessed December 31, 2012.

    Revision Information

  • LiveWell personal health survey

    How healthy are you really? Find out – free.Learn more

    It's time to stop guessing. If you want to make some changes but just aren't sure how, the free personal health survey from LiveWell is a great place to start.

  • HeartSHAPE Spotlight

    At risk for a heart attack? Learn more

    Fight heart disease and prevent heart attacks. HeartSHAPE® is a painless, non-invasive test that checks pictures of your heart for early-stage coronary disease.

  • Calories and Energy Needs

    Calorie NeedsLearn more

    How many calories do you need to eat each day to maintain your weight and fuel your physical activity? Enter a few of your stats into this calculator to find out.

  • Ideal Body Weight

    Ideal Body WeightLearn more

    Using body mass index as a reference, this calculator determines your ideal body weight range. All you need to do is enter your height.

  • Body Mass Index

    Body Mass IndexLearn more

    This tool considers your height and weight to assess your weight status.

  • Can we help answer your questions?

    Wellmont Nurse Connection is your resource for valuable health information any time, 24 hours a day, seven days a week. Speak to a Nurse any time, day or night, at (423) 723-6877 or toll-free at 1-877-230-NURSE.