Wednesday, July 11, 2012

Conflicting studies on blood donation and insulin sensitivity

After posting about my experience (so far) with blood donation I did some searching and found two published studies that seem to have opposite conclusions.

One found that blood donors with lower iron stores did not have any different response to glucose tolerance tests. The other found that those with lower iron stores had higher insulin sensitivity and lower insulin secretion. And a health blogger talks about these issues in depth. Hmmm...

It was hard for me to really tell if they used the same glucose tolerance test. I will keep an eye on my blood sugar measurements over the next couple of weeks and probably donate again in August. I am curious about this.

As a side note: I know that a glucose tolerance test would destroy me (and most T1 diabetics?). Non-diabetic people who eat low-carb/ketogenic often fail glucose tolerance tests. When eating a ketogenic diet you develop a type of insulin resistance in the tissues that spares glucose for the tissues that absolutely need it. For instance, parts of the brain can only run on glucose. So in the scarcity of glucose the tissues will down regulate their glucose absorption to make sure that the glucose is reserved for the tissues that need it. Because of this mechanism, I don't handle changes in my glucose intake very well. I run well on fat and protein, and if I throw more carbs or sugar into my diet I get a disproportionate rise in BG. I have to take more insulin than my carb factor indicates to control fast-acting carbs. I know that I could become acclimated to a higher level of glucose in my system, but I prefer to keep things ketogenic because it's the only way I have been able to achieve stable blood sugars.

What would you do to handle 75 grams of liquid carbs?


  1. Last week I went hypo (42 mg/dl) and was really low on stuff to treat it with so I bought a bottle of soda, something with about 75 grams of sugar in the bottle. Over the following two hours I drank the whole thing without coming up to 100... it was the first time I'd drank soda in that quantity, ever, and I'm wondering what the heck.

    But anyways. If I prebolused by about 20-30 minutes for 150 grams of carbohydrate, drinking 75 grams of glucose would probably do very little to my blood sugar, and I'd need to eat another 75 grams of glucose about two hours later.

    If I didn't take insulin and hadn't just been running around or traveling or sick or anything that makes sugar not affect me as much, then I would expect 75 grams of glucose to raise my blood sugar by about 300-400 mg/dl, which would mean that if I went in with a good number I'd expect to finish with a blood sugar of 400-600 mg/dl. But blood sugars that high tend to make me vomit, which raises my blood sugar further... it would be a bad situation.

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