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With all the talk about resistant starches in the media lately, I thought I may as well do an n=1 glucose tolerance test on myself to see if all the hype is for real. There are many claims of the health benefits of resistant starches, but in this experiment I wanted to test the claim that they are not digested until the large intestine, so they don't raise the blood sugar like "normal" starches. For those that don't know, an n=1 test is the personal equivalent of a short (very short) term clinical trial with one subject. Since I am insulin dependent and make no endogenous insulin, it is very easy for me to see the effects of various foods on my blood sugar.
In this case, I chose to test the effective carbohydrate load that baked and chilled yams have on this diabetic. I waited 4 1/2 hours after my last food or insulin intake. I used a time of day that I have used numerous times before for n=1 tests so I have confidence that basal metabolism and insulin are canceled, so I will get a true as possible test with my non clinical equipment. I use a Freestyle Freedom Lite BG meter and test strips. This has proven in the past to reproduce results very well.
I baked a small, 114g, fresh yam in the oven at 350deg F for 45 minutes, then I chilled it in the refrigerator at 35 deg F for 4 hours. At 1300 hrs (1:00 PM) I ate 34 grams of the yam with skin. No seasonings were added. I did not take a bolus dose of insulin to cover the 8 net grams of carbs that that quantity of yams is supposed to contain. The following are my blood glucose readings starting at 0 minutes, then every 30 minutes for 3 hours.
1300 - 77 mg/dl
1330 - 78 mg/dl
1400 - 84 mg/dl
1430 - 89 mg/dl
1500 - 89 mg/dl
1530 - 80 mg/dl
1600 - 77 mg/dl
This result closely followed the curve from my Medtronic 722 CGM (constant glucose monitor). As you can see, the 8grams of yam carbs raised my BG 12 mg/dl at 2 hours, then started tapering off within an hour, finally reaching the starting value by the 3rd hour. I know from many past trials and experiences that 8 grams of pure dextrose will raise my blood sugar 52 mg/dl within 1 hour.
At the end of the test I finished the rest of the yam (19 g net carbs) without an insulin bolus. I checked my BG 2 hrs later (normal postprandial interval) and it had risen 25 mg/dl, which is pretty consistent with the rise per gram I got earlier. The total of 27 grams for both portions would be expected to raise my BG by 175 mg/dl and keep it up for many hours.
So, initially it looks like there may be something to this resistant starch business (at least in my body). Of course I'll need several more n=1 tests at different times of day to be able to say for sure. It's a good start.
Diet Calendar Entries for 04 April 2014:
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1275 kcal
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Fat: 58.00g | Prot: 85.15g | Carb: 116.03g.
Breakfast: Walnuts, Blueberries, Fage Total 2% Greek Yogurt, Sweet Leaf Liquid Stevia. Lunch: Yam. Dinner: Havarti Cheese, Kirkland Signature Normandy-Style Vegetable Blend, Metamucil No Carb Metamucil, Sabatino's Smoked Mozzarella with Artichokes & Garlic Chicken Sausage. Snacks/Other: Sweet Leaf Liquid Stevia, Hershey's Natural Unsweetened Cocoa, Coffee (Brewed From Grounds), Nutmeg (Ground), Cinnamon. more...
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2250 kcal
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Activities & Exercise:
Resting - 13 hours, Sleeping - 8 hours, Walking (slow) - 2/mph - 2 hours, Yard Work (gardening) - 1 hour. more...
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