May 16, 2006
Diagnosis and Symptoms
Question from Grand Forks, North Dakota, USA:
I will be going to an endocrinologist next week. I believe I may have some kind of intolerance. I have lows sometimes soon after I eat (anywhere from one to three hours afterward). One day, I was 226 mg/dl [12.6 mmol/L] 20 minutes after two hot dogs, a handful of chips, and a Pepsi. Surprised at the number, I checked at an hour and my blood sugar was 259 mg/dl [14.4 mmol/L]. At two hours or so, I was back at 121 mg/dl [6.7 mmol/L] and feeling slightly shaky. I seem to be higher than the norm after two. On average, I am 140 mg/dl [7.8 mmol/L] after meals. Fasting, and testing with a home glucose meter, I am 96 to 110 mg/dl [5.3 to 6.1 mmol/L]. In the morning, I can tell if I am over 100 mg/dl [5.6 mmol/L]. I feel a pit in my stomach like I need to eat. In August 2005, my A1c was 5.6, and my fasting blood sugar, venous draw, was 96 mg/dl [5.3 mmol/L]. So, the doctor didn’t feel a need to do an Oral Glucose Tolerance Test (OGTT).
I have PKD (polycystic kidney disease) and am 33 years old. I had been spilling protein in my urine so a nephrologist put me on a blood pressure medication to lower my blood pressure and prolong my kidney life. At that appointment, my venous glucose was 50 mg/dl [2.8 mmol/L]. That was 90 minutes after eating breakfast. I wasn’t shaky, but had a slight headache. Usually, when I am shaky, I am in the 70s or 80s mg/dl [3.9 to 4.3 mmol/L].
I am hoping for an OGTT. I see on the web that some have you drink 75 grams of carbohydrates and test at two hours. Then, on here, I see that you test at 30 minutes, one hour, two hours, and three hours. Should I ask for a specific OGTT? Have you heard of a situation like mine?
Answer:
Yes, there are many people who have symptoms like yours. First, unless that glucose of 50 mg/dl [2.8 mmol/L] was immediately ran or collected in a tube that contains material that immediately stops red blood cells from metabolizing glucose, there is a question as to whether that was a falsely lowered glucose. Second, people can have symptoms with rapidly falling glucose without having an absolutely low glucose. You probably have some degree of insulin resistance. You eventually make enough insulin to bring glucose down, but the braking mechanism for insulin secretion may not be smooth and you may overshoot a little. If you are going to have an OGTT, the only test that is really pertinent is the 75 gram OGTT with zero and 120 minute glucose measurements. Looking at the response to glucose is not specific for any hypoglycemic disorders. However, it is a sensitive test for the diagnosis of type 2 diabetes. An additional caveat is that patients intending to have an OGTT should make sure to take in liberal amounts of carbohydrates for at least three days prior to the test (100 grams per day) so as to prevent false positive test results.
JTL
