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Testing For Hypoglycemia And How Your Doctor Can Help

By Dr George Samra, MB, BS (Sydney), FACNEM

The correct test for Reactive Hypoglycemia is a G.T.T. The test should be ordered by the doctor as follows: G.T.T. – 4 hours. All 1/2 hourly readings. No special diet prior.

The Glucose Tolerance Test is the classical test used in diagnosing Diabetes. The Diabetic test is a 2 hour G.T.T. with just 3 readings, the fasting, the 1 hour and the 2 hour. This test is not correct for testing Functional or Reactive Hypoglycemia. With Hypoglycemia one is interested in the full reactions to a sugar load. In both cases a 75gram load of glucose is given to the patient after having collected blood for the fasting level. With Reactive Hypoglycemia the emphasis in on the word “Reactive”- one is looking for the sugar reactive phenomenon in which the blood sugar either drops suddenly or falls very low. Part of diagnostic criteria for Hypoglycemia is the rate of fall of blood sugars, hence the relationship between consecutive readings is very important. Sudden drops in blood glucose will usually trigger an adrenaline response and subsequently adrenaline symptoms such as nervousness, shakiness, dry mouth, irritability, agitation, neck stiffness and sometimes palpitations or a racy heart.

With Reactive Hypoglycemia one is also seeking to ascertain how low the blood sugar may go as this in fact is one of the measures of severity. The brain is dependent on blood glucose as it’s only fuel supply under normal circumstances. When the blood glucose falls below a certain level, usually 3.6mm/L, there is a lack of available fuel to the brain and symptoms of brain starvation will occur – these include tiredness, moodiness, depression, forgetfulness, poor concentration and cloudy headedness.

The purpose of the G.T.T is to clarify how well one tolerates glucose and by doing it properly one is able to see if the blood sugars drop too rapidly or fall too low. It is important that the glucose tolerance test is done accurately and properly. The following rules apply:

1.    Fasting for at least 10 hour prior. Usually this means fasting from 10.00p.m. the previous night.

2.    Once the fasting sugar level has been collected. A 75gm glucose load is given to the patient. In children this may be adjusted according to their size, however usually a 50gm glucose load is suitable for the vast majority of children.

3.    The pathology lab should be made aware that we are not trying to diagnose Diabetes but rather Reactive Functional Hypoglycemia. For this reason the doctor is requesting a longer test, i.e. 4 hours instead of 2 hours as well as all 1/2 hourly readings.

Does Insulin Need to be Measured?
Usually Insulin levels do not need to be measured. However, when the doctor suspects an Insulinoma (Cancer of the head of the Pancreas) and also in the case of an obese patient insulin levels may prove very useful in clarifying the diagnosis.

Determination of the Glucose Tolerance Test Results
The different types of Hypoglycemia have been classified based on the Glucose Tolerance Test. If the blood glucose levels falls below 3.6mm/L (65mg per 100ml) then Absolute Hypoglycemia is present. If the blood glucose level drops rapidly i.e., greater than 1.6mm/L (30mg per 100ml) in 1/2 an hour or greater than 2.6mm/L (50mg per 100ml) in 1 hour, then Relative Hypoglycemia exists. If the curve has a sharp gradient and numbers below 3.6mm/L together, then is regarded as the classical Reactive Hypoglycemia. The lower the blood sugar readings and the larger the gradient the blood glucose falls the more severe is the diagnosis. A fasting Hypoglycemia alerts the doctor the possible diagnosis of Insulinoma. The flat curve response and its implications have also been described elsewhere on this web site.

See results of a GTT and here.


What to Say to Your Doctor & How to Approach Your Doctor
Most doctors have a problem understanding Reactive Hypoglycemia and this frustrates them. For this reason I’m including a letter to the doctor that you should download and which should help you get a satisfactory response from your doctor.


Web Site http://www.hypoglycemia.asn.au

Dear Doctor,

Your patient has identified with the many symptoms suffered by patients with Reactive or Functional Hypoglycemia. As you well know, Hypoglycemia is low blood sugar, however Reactive Hypoglycemia is a sugar reactive phenomenon (and is not Diabetes.) After a sugar load such as a soft drink or cake, patients with this condition often suffer symptoms due to a sudden drop in their blood sugars, which typically occurs between 1 1/2 hours and 2 1/2 hours after the sugar consumption. Typical symptoms of Hypoglycemia include tiredness, poor concentration, moodiness, depression, forgetfulness, nervousness and irritability.

The brain relies on glucose as its only fuel under normal circumstances. The symptoms of Hypoglycemia relate to the fact that the brain is not being fueled properly at some point in time. In order to investigate this condition and help your patient please order a Glucose Tolerance Test as follows:
GTT 4 Hours. All 1/2 Hourly Readings. No Special Diet Prior.

This is the correct way to order a test for Reactive Hypoglycemia. The patient is usually given a 75gm load of glucose soon after the fasting level has been collected. With the prolonged GTT and with the 1/2 hourly readings one is able to ascertain both the rate of fall of blood sugars as well as whether they in fact fall below the Hypoglycemia line that is usually 3.6 mm/L (65mg per 100ml). Guidelines for interpretation of the Glucose Tolerance Test are available on the web site or directly from the Hypoglycemic Health Association.

Thank you sincerely for your co-operation. This test may help to clarify many troublesome symptoms that your patient has been experiencing.


Yours sincerely,
The Hypoglycemic Health Association.


55 Responses

  1. Susan says:

    I should also note that we’ve noticed extreme hyperactivity if he eats or drinks simple sugars (i.e. candy/junk) without anything else with it.

  2. billyboy says:

    My daughter has suffered with severe depression and anxiety for three years. We believe that this was triggered by an antibiotic and eventually found a doctor who agreed with us (most thought we were, shall we say unsophisticated). Anyway we noticed after a lot of trial error and observation that we could manage her with a low GI diet quite successfully. In fact we got her through a whole semester of uni like this. Unfortunately I went away for three days leaving her with plenty of prepared food that she didn’t eat. She also drank three litres of apple juice (empty carton next to her bed). When I returned home we were shocked to find that she had been admitted to hospital (again). I told them to put her on a low GI diet and she would be just fine but they wouldn’t believe me. She deteriorated massively and after much complaining from me they gave her a GTT. Sadly they reported that there was no glucose issue and promptly told her so. The next month was an absolute nightmare for us, she refused to trust her parents advice and wouldn’t eat low GI anymore. Long story short she was admitted to the mental health hospital where they refused to put her on a low GI diet too (because they think it is nonsense)and are not at all motivated to give her our doctor’s prescription. She also has immeasurably low chromium, iron so low she needs an infusion and low zinc and selenium. After ten blood tests and eight hospital stays nobody noticed!! It is so frustrating because I know that she will improve massively in 48 hours if they would only let me prepare her meals. I suspect that this is too threatening for them, they will not even think about trialling this. This has been heartbreaking for her family.

    • Jurriaan Plesman says:

      This is the trouble when you deal with an arrogant profession that believes in drugs only. This is exactly the reason why we have a created a Hypoglycemic web site: to educate the public and the profession. It may help if you allow your daughter to have a greater say in her own recovery by educating her on the connection between Mood disorders and Nutrition. Perhaps you should get the assistance of a Nutritional Doctor from ACNEM at: http://www.acnem.org/modules/mastop_publish/?tac=23

      • Bill Wormald says:

        Thanks for your comment and understanding. We are
        fortunate to have found an excellent nutritional doctor in
        Perth who quickly recognised the symptoms and prescribed a
        chromium supplement (hopefully to assist with the
        hypoglycemic attacks), and selenium and zinc (hopefully to
        assist with the mental health issues). He also requested a
        stool sample to examine her microbiome for dysbiosis.
        Unfortunately my daughter has been convinced by the
        hospital that her parents (and presumably her doctor) are
        wrong. They do not seem at all motivated to follow our doctor’s advice or give his prescription. I am sure that they think I am a bit strange too, to suggest that a low GI diet could help in any way. It will be difficult to regain our daughter’s trust. In the meantime I will try to obtain her GTT graph to get a second opinion from another nutritional specialist (this is frustrating as we have full confidence in our existing doctor). If I can obtain this Would you be available for such a professional consultation, or would we need to choose a second doctor from your web site list?

  3. Amber wise says:

    What if my docter refuses to do these tests.

  4. Tamra says:

    I had a 7 hour glucose test when I was 16. The doctor informed my mother that I have hypoglycemia. I had a great doctor when I was about 20 who told me to stay away from sugar and simple carbs. I am now 43. For most of my life I have kept the symptoms at bay. It is only if I get hook on sugar again that I get bad symptoms. With all the new science and information, I am curious how to know if I have reactive or absolute hypoglycemia. Is there a way to determine which it is without more testing? I am sure it does not matter as far as diet, exercise and self-care, but I would like my doctor to be more aware. He does not understand that when I describe a “crash” I am not describing diabetes. He continues to order fasting blood draws. It is frustrating.

    • Jurriaan Plesman says:

      The best thing to do is to refer your doctor to this web site. If he is not interested, get a new doctor and tell him why.

  5. Jurriaan Plesman says:

    There is very little you can do with narrow-minded doctors. That’s the way they are trained. But you can CHOOSE your own nutritional doctor doctor. They are trained in both conventional AND nutritional medicine.

  6. Sandra says:

    I have been suffering from strange symptoms since 2005. Anxiety, depression, panic attacks etc. In last year I was admitted to the hospital due to brain abcess caused by mainly oral bacteria and strep milleri. Deterioration in my health has been progressive, looking back. I have never understood what could cause this. My life was never more stressful than other peoples etc…but looking back, there were some symptoms I never addressed to doctors such as shivering, fog brain, etc. At times I would find myself shaking in bed without knowing why. Post abscess surgery I found myself for a week having extreme salt urges at 7pm every night. These went away after a week or so. Lab tests showed salt levels all ok. Reason why I am looking into a hypoglycemic connection is due to a friend who suggested this to me because of the behavior in the hospital and salt urges. The more I read about hypoglycemia, the more I am thinking my immune system must have been effected if this is the case…..hence the abscess and recent seizure, which I am absolutely baffled by. I know there is a risk of one after this type of surgery, but my recovery as docs describe it has been a miracle. Why seizure? Here is my overall condition:

    – recent thyroid tests, b12 tests ok
    – vit D good 39.2
    – low blood pressure
    – rapid pulse (always)
    – irregular heart beats
    – opthomological migraines (less now after supplementing magnesium)
    – blurry vision with floaters (floaters on and off)
    – nearsighted
    – difficulties adjusting vision during night
    – cold in extremities
    – feeling of something in throat (lower part) at times (on and off, almost as if that area tends to swell like a joint)
    – neck tension
    – shivering/small tremors in hands, legs on and off

  7. jenn says:

    I had a dizzy spell last Sunday it made me feel like I had been so drunk all I wanted to do is pass out. I have heart problems I was born with . ambulance people checked me out said vitals where grate. They said it might be vertigo and seen a dr today said I may have this stuff but he did not check me for it. I some times get the dizzy spells right before I get badly sick with like a cold or somthing. I don’t know what’s wrong and I don’t like it. Any suggestions?

    • Jurriaan Plesman says:

      I am not sure whether this is related to hypoglycemia. The best thing to check it out with a doctor and get checked for pre diabetic hypoglycemia.

  8. Barbara Nock says:

    On and off in my life I have dizzy spells. Not on a regular basis but when I have a bad one, as I did last night, it is awful. The room spins and I feel sick but do not vomit. I believe I had low blood pressure as I grew up but thought this changed as I got older but the spells continue. Some are short and I just keep quiet and still until they pass but the bad ones are with me for quite a few hours. This is scarey and I have been tested for diabetes but that test was negative. Do you think maybe hypoglycemia could be the reason. I have a few of the symptoms mentioned but not all of them.

  9. Toni says:

    I took a glucose tolerance test and these were my results:
    1st draw-60
    2nd draw (after 1 hour)-106
    3rd draw (after 2 hours)-80

    Can someone tell me if this is good or bad?

  10. Simon says:

    Is there a good nutritional doctor in sydney who will perform a GTT? I have been diagnosed with menieres and hypotension and yet there is no family history. There is family history of diabeties though type one and two. I read of links from menieres to hypoglycemia. Thank you

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