how low?

How low is too low for blood sugar?  I was wondering this after running across a multitude of “low” cut offs while looking up causes for hypoglycemia.  It’s a funny old thing, hypoglycemia.  One of the controversial diagnoses (1, 2, 3) it seems.  What exactly is so controversial about passing out and convulsing?

ine graph of author's glucose levels at fasting and .5, 1, 2, and 3 hours after oral glucose administration. Also plotted is "normal" curve for glucose.

It’s been a (knock on wood) long time since that’s happened.  Last was in 2004.  I attribute this improvement to three factors.  (a) I was dating a diabetic from 2000 to 2005 and he was able to check my blood sugar while I was symptomatic and show that indeed, symptoms = low blood sugar for me which allowed me to (b) have a slightly better awareness of when my sugar might be low and treat it pre-pass out level; and (c) after adolescence it seemed that I stabilized somewhat, or at least I was less easily sent into a low blood sugar spin.  Since having the glucose tolerance test in 2010 and getting my own glucose meter, I’m slowly getting better at recognizing very early symptoms of low blood sugars.  I still suck rather a lot and this is because I will notice but then dismiss symptoms.  Low grinding headache or nausea are both too easily dismissed for me.  Craving something like a root beer or other soda I tend to ignore now that I am trying to drink less soda (totally killing my teeth).  But these are my early symptoms, and I ignore them the same way I ignore when I’m getting overheated…they come on slow, I don’t want to stop what I’m doing and deal with it so I ignore it, and when I do I am rewarded with my body coming to a screeching halt and me on the couch for an hour of feeling like total hell.  So I need to get better at attending to these symptoms.  I know.  It’s on my to do list.  Right up there with “pee in jug for endocrinologists”.

My glucose tolerance test (GTT) results from last year are graphed here.  On the insulin levels, I didn’t have values for 1/2 hour.  Not sure why not.  It seems like that would have been good, especially since my insulin (as measured) didn’t get terribly high at all.  I also noticed that the lab’s reference ranges for glucose were not very elucidating:  tere were ranges given for fasting (65 – 99 mg/dL) and for the 2 hour mark (65-139 mg/dL), but the other times only had a low cut off (of 65 mg/dL).  From what I can see, it looks like they didn’t give the highs to avoid stepping on any doctor’s interpretation toes – i.e. there are some different cut offs for “too high” or “not normal” glucose levels during the GTT.  But those can be found online.  E.g., Carpenter and Coustan 1982; WebMD; lab tests online.  What you can’t find is cut offs for low values.  Is 65 really the low end of “normal” throughout a GTT?  I seriously doubt it.

ine graph of author's insulin levels at fasting and 1, 2, and 3 hours after oral glucose administration. Also plotted is "normal" curve for glucose.

Regardless, I did get below the (I think rather) low cut off of 65 at the 2nd and 3rd hour mark.  I’m glad this wasn’t one of those 5 hour GTT.  I’m thinking of doing a repeat at home with the finger stick…I know that finger sticks don’t measure in the same way as samples from a vein.  I will adjust accordingly if I want to compare absolute values.  Mostly, I’m interested in the curve.  I’d like to know if it has changed, because it seems to me like my blood sugar is spending a lot of time down low lately.

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