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Diabetes Overview
Types of Diabetes
Glucose Meters
Long-term Complications

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Diabetes Diagnosis & Testing

If you think you are developing diabetes, a full medical workup should be done including your full medical history (interview) and a full physical examination. During your medical interview, you should be asked questions pertaining to your present illness, your past medical history, relevant family medical history, current medications, allergies, etc.

Some physicians may explore the possibility of diabetes by a simple urine test. If your physician suspects diabetes, you may be asked to take a blood test.

Blood Glucose Testing
  • Fasting plasma glucose exam requires the patient to not eat or drink the night before the examination. If the fasting blood glucose level is greater than 125 mg/dL, another measurement on a different day may be taken to confirm your diabetic state. If your fasting blood glucose level is greater than 100 mg/dL, you are in danger of developing diabetes soon. This intermediate level is sometimes known as “pre-diabetic” or having an “impaired glucose tolerance.”
  • Glucose Level
    Test Result

    70 to 99 mg/dL (3.9 to 5.5 mmol/L)


    100 to 125 mg/dL (5.6 to 6.9 mmol/L)

    Pre-diabetes (Impaired fasting glucose)

    126 mg/dL (7.0 mmol/L) and above

    Diabetes (must confirm with an additional test )

  • Oral glucose tolerance test involves an overnight fast. Before blood is drawn, the patient should be resting comfortably (no smoking, no alcohol nor coffee before the exam!). After the fasting blood is taken, the patient is given 75 grams of glucose to drink. Another blood sample is taken 2 hours after the glucose drink. If this sample is greater than 200 mg/dL, you are probably diabetic. If your sample is greater than 140 mg/dL, you are considered pre-diabetic.
  • Glucose Level
    Test Result

    < 140 mg/dL (7.8 mmol/L)


    140 to 200 mg/dL (7.8 to 11.1 mmol/L)


    > 200 mg/dL (11.1 mmol/L)

    Diabetes (must confirm with an additional test )

  • Gestational Diabetes is tested for with a Glucose Challenge Test (GCT) or Gestational Glucose Screen Test. It is generally taken between 24 and 28 weeks of pregnancy to check for gestational diabetes. The GCT is given to help screen for possible gestational diabetes. A positive result does not mean you have the condition. A more definitive exam called the Glucose Tolerance Test (OGTT)will need to be taken.
  • Glucose Level
    Test Result

    <130 mg/dL (7.2 mmol/L)


    130* mg/dL (7.2 mmol/L) and over

    Abnormal; further testing needed (OGTT)

    Glucose Level
    Test Result


    > 95 mg/dL (5.3 mmol/L)

    Two or more values over the limit indicates gestational diabetes


    1 hour after drink

    > 180 mg/dL (10.0 mmol/L)
    2 hours after drink > 155 mg/dL (8.6 mmol/L)
    3 hours after drink > 140 mg/dL (7.8 mmol/L)
  • Glycosylated hemoglobin (HbA1c) test measures what your blood is doing over its lifespan (roughly 120 days). Excess glucose in the bloodstream attaches to the hemoglobin in red blood cells in a process called glycosylation. Once attached, the glucose remains with the red blood cell for the duration of the red blood cell’s life. Thus, a ratio of glycosylated hemoglobin to normal hemoglobin can accurately give a picture of glucose levels of a patient over the past several weeks or months. A HbA 1c result of greater than 6.5% is highly suggestive of excess glucose in the blood. The HbA 1c test is usually administered to known diabetics every 6 months.

Urine Testing

  • Urine is obtained 1-2 hours after a meal. The urine is tested for glucose and ketones. Excess glucose in the urine calls for further examinations.
  • Urine testing is often skipped by some physicians because results vary so greatly among individuals. A low renal threshold for glucose, alimentary glycosuria and pregnancy can cause distorted urine tests.

Fingerstick blood glucose tests

  • These are used as rapid screening tools. These tests are often inaccurate at very high or very low levels of glucose in the blood. However, known diabetics use this tool to measure their daily glucose levels at home. Within a specified target range, fingerstick blood glucose tests are relatively accurate, thus this test is a great way for diabetics to monitor themselves at home.
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This information is not a substitute for your doctor's medical advice.