October 17, 2007

Fructose Raises A1c?

Jackie Patti posted an interesting comment to my earlier post about my disappointingly high A1c.

It seems that Gary Taubes' new book discusses this and reveals that fructose causes more glycosylation of proteins than does glucose. However, when we test our blood sugar we don't look for fructose, we only measure glucose, a different sugar.

Hence a diet that is high in fructose may raise A1c, and with it the risk of heart disease and other organ damage, in a person whose blood glucose is very well controlled.

Most people think of fructose as "fruit sugar" as it does occur naturally in fruits and in vegetables like tomatoes and squash which are technically fruit.

But this is only half the story. Sucrose, common table sugar, is 1/2 glucose 1/2 fructose. Honey, which is used in many health foods is higher in fructose than in glucose. And of course high fructose corn syrup is added to most packaged foods including ones you would not expect to have it, things like soup.

It is hard to find nutritional information that distinguishes between the different types of sugars found in other foods, but some helpful web sites list foods to be avoided by people who have a medical condition in which they are not able to metabolize fructose. These sites list wheat as being on the list of foods to avoid, though not rice.

Here's a web site that has the complete breakdown of sugars for many foods, where available. http://www.nutritiondata.com/

So heightened Fructose consumption may explain the rise in my A1c. I have been eating a lot of fresh farm-grown tomatoes and more chocolaty/sugary stuff than is probably good for me, thanks to the extremely good control I've gotten with my insulin. This new information suggests that my higher than desired A1c might be a result of tilting sugar intake too much towards fructose.

If that is the case, much of the problem has already been solved by the turning of the seasons. No more fresh farm stand corn or tomatoes. Back to glucose for treating lows. I'd been using some sinfully yummy hard candies, and that may also have been causing the rise.

I've got the Taubes book on order and can't wait to read the whole thing. Though once I have I probably wont' be able to ever again eat anything I feel like eating without dismay.


Chrissie in Belgium said...

Jenny, as you know I am a "veteran" T1. My HbA1c is low at 5.2. I never eat fruit or sugar and definitely keep away from all foods that have high a glycemic ondex, BUT when I was in Sweden this summer and afterwards when the bakery was closed here in Belgium, I continued to substitite the prefabricated dry Knorr soup. I was unable to freeze enough of the bakery bread! For hypos I DO use sugared coke, but usually very small amounts are necessary to treat hypos. PerhapsMaybe this has no significance for you!

Jenny said...


I believe that the Coke sold in Europe uses Sucrose where that sold in the U.S. uses High Fructose Corn Syrup.

The HFCS is implicated in causing bad lipids, too.

kwollard said...

hey, I think you're def. on to something:


and most especially this:


Gary Taubes' book is v. good, but has a few holes and at least one glaring error, in which he
implies that the uterus rather than the ovaries is the source of estrogen production.

Jenny said...


That second link, connecting Fructose levels with Retinopathy is disturbing.

I don't know enough about fructose metabolism to begin to know where to start on this one. Something new to study up on!

Chrissie in Belgium said...

Yes, coke in Belgium uses sucrose. I did not know that the coke in the States was based on high fructose corn syrup! Sucrose works much quicker to remove a hypo than fructose!