Still Hungry: The Mixed Meal Tolerance Test leaves something to be desired


As I have previously discussed, I am participating in the Protégé Encore study, which is an anti-CD3 monoclonal antibody clinical trial that is trying to prove the effectiveness of an investigational drug called teplizumab.  We all know that type 1 diabetes is an autoimmune condition where autoantibodies are attacking and killing off the body’s pancreatic beta cells.  Among other things, beta cells produce insulin, so damaged beta cells lead to decreased levels of insulin production… which leads to a diabetes diagnosis.  I enrolled in the Protégé Encore study and got a nice, long infusion of this drug, teplizumab, so (hopefully!) my body is now doing things a little differently.  As my study doctor explained to me, teplizumab acts as a body builder standing outside of a restaurant where autoantibodies hang out.  As the autoantibodies walk out of this restaurant, the body builder steps out of the dark alley and knocks out the autoantibodies.  They are not dead; they eventually wake up and wander “home,” back to their usual hang-out spots.  They go back to doing the beta cell killing they were doing before, but because of the harsh blow from Body Builder Teplizumab, it takes them about a year to fully return to work.

In order to test the effectiveness of this drug, I go to the hospital on a regular basis for check-ups and blood draws.  The lead doctor for this study monitors the levels of all kinds of things in my blood, but the thing that is perhaps most telling is the level of something called C-peptide.    My understanding is that C-peptide is some kind of substance that is left over after your body’s insulin is produced and used.  C-peptide is only created and left over by “real,” self-made insulin; not the kind that I squirt into my abdomen.  Doctors love to look at this, therefore, because it is one tell-tale sign of insulin production.

For each of my follow-up visits since I had the infusion back in May, I participate in a blood draw and occasionally some additional procedure.  Coming up for my October visit, I will have a Mixed Meal Tolerance Test.  (Other contributors have already covered the MMTT experience.)  The MMTT consists of drinking a breakfast shake (I hope it’s chocolate!) in a matter of minutes, and then sitting in a chair while the hospital staff documents my blood sugar levels every 15 to 30 minutes.  It’s a mixed meal, you see, meaning it’s not just glucose that they’re pumping into you; it’s a breakfast shake.  It’s full of things other than glucose, such as:  Water, sugar, corn syrup solids, milk protein concentrate, vegetable oil (canola, high oleic sunflower, corn oils) and less than 0.5% of soy lecithin, carrageenan, salt, natural and artificial flavor, vitamin A palmitate, beta-carotene, ascorbic acid, sodium ascorbate, vitamin D3, vitamin E acetate, thiamine hydrochloride, riboflavin, niacinamide, vitamin B6 hydrochloride, folic acid, choline bitartrate, vitamin B12, biotin, calcium pantothenate, vitamin K1, calcium carbonate, ferrous sulfate, potassium iodide, magnesium phosphate, zinc sulfate, cupric sulfate, potassium citrate, potassium chloride, sodium selenite, chromic chloride, sodium molybdate, manganese sulfate.  You know, like the ingredients that make up a basic meal.  A basic meal, that is, if you happen to like drinking an unsatisfying breakfast shake—and nothing else—for the first four hours of your day.

(Even this image gives way too much credit to the breakfast shake I will be drinking.)

The doctors leading the study don’t really care about how full I feel, though, I suppose.  They care about how my body responds to this “meal.”  They care about blood sugar levels and C-peptide levels and whatever other information they can gather from my blood.

I’ll let you know how it goes.  Maybe they’ll let me fill out a comment card this time.  For now, I suggest you stick to your high-protein, complex carb breakfasts of champions.

P.S.  Please feel free to comment with your questions and corrections!

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7 years ago

I have to have an MMTT on Monday. It sounds delightful.

Dr. Margaret A. Morris
12 years ago

Haha, I don’t envy your breakfast shake, but I do envy your chance to keep your C-peptide around ;) Do you know what your levels were last they checked, and what they are for non-diabetics? What do the doctors need to see to assume the treatment is working vs. not?

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