Human Self Experimentation - The OGTT

Has anyone performed their own homemade Oral Glucose Tolerance Test (OGTT) (

***Warning, do not attempt this if you are T1, are insulin dependent or have a markedly deficient insulin response

It is one thing to measure blood sugar before and 2 hours after meals, but if you really want to see how your poor pooped out pancreas is handling life, nothing beats the good ole OGTT. This is especially insightful to the T2 as it will tell you how much phase 1 insulin response you have, how high your blood sugar reaches and overall how well you tolerate carbs.

In my case, I've struggled with my diabetes for some years and have really not handled carbs well at all. Usually, I can't handle more then 10-15 grams of carbs and still be below 140 mg/dl after two hours. But over the last few years, at times when I've changed my medications, I've had sudden and seemingly dramatic improvements in my diabetes. I call them my honeymoon's. Well, I changed my medication this week and I decide to do another OGTT. Here is my method and result:

Choose a start time (usually morning) with as near a normal fasting as possible (preferably under 100 mg/dl, but just do you best). Prepare your weapon of choice. 75g of carbs. It is preferable to use glucose. You can probably use any simple carb. I chose to use HFCS-free "maple syrup," mostly made from corn syrup and sugar, so pretty high in glucose. I mixed it in 1 cup of milk, for a total of 75g.

So start by measuring your fasting, ingest the 75g of carbs and then measure your blood sugar every 15 minutes for 2 hours. A normal "non-diabetic" response will not rise above 140-160 mg/dl. Most diabetics will rise much higher but the key is of course returning to less than 140 after 2hrs. As a test for diabetes, the WHO (and others) interpret being > 140 mg/dl, but less than 200 mg/dl at 2 hours as impaired glucose tolerance. Being above 200 mg/dl at 2 hrs is full blown diabetes.

Here are the results of my OGTT today:

Time - Glucose reading (mg/dl)

0:00 - 93

0:15 - 153

0:30 - 218

0:45 - 174

1:00 - 196

1:30 - 105

2:00 - 73

2:30 - 64

This result is in stark contrast to my previous OGTTs. While I went a bit high, and I had some reactive hypoglycemia, at least for now, I can probably eat some reasonable level of carbs.

Previously, my so-called "honeymoons" have lasted about 2-3 weeks. I'm thinking of doing the same thing when my blood sugar control takes a turn for the south.

Has anyone else done their own OGTT? Should I share this with my doctors?

I’ve never done anything like this…scares the dickens out of me…Like you, I keep my carb intake low.
How do you know if the results are due to insulin resistance or low insulin production or both? How does this test give you a measure of your phase 1 insulin response?
I don’t understand…If I could understand what I might learn from doing this at home, I would be willing to try it.
What would you gain by telling your doctors? If it would help them to help you, then by all means tell them.
Forgive me for pointing out the obvious…as you said you have been dealing with diabetes for a long time. The simple carbs will go through you much quicker than complex carbs so you would need to be careful about applying what you learned here to how all carbs might affect you.

Normally, ingesting 75g of carbs would have been a pretty stupid thing for me to do. But the “honeymoon” thing is pretty dramatic, my fasting drops to normal levels and my carb intolerance dissappears. It has happened a few times. You can’t tell if you have insulin resistance or insulin deficiency without measuring insulin levels, which you can’t do at home. The phase 1 response releases stored insulin in the first 15 minutes, as you can see, my blood sugar shot up, I had a weak phase 1 response. On the other hand, after an hour my pancreas kicked into high gear with a phase 2 response and full restored my blood sugar. The whole point of the simple carbs is to have them hit you all at once during the test. If I eat to keep my blood sugar tightly controlled, I “never” eat simple carbs and I usually eat to Dr. B levels. What I have learned here applies only to my honeymoon. I will know when my honeymoon is over, my fasting blood sugar will rise 30-40 mg/dl, and I will lose my tolerance to carbs.

Being a T1, I’d never do this.

One gram of glucose raises my BG 10 pts. At 75 carbs without insulin, I’d be in the ER with an IV.

Wow, nice response from the ol’ pancreas. I’m an insulin dependent T2 and have never had an OGTT. I’ve thought of stopping my insulin for a day or two and trying this at home to see what’s left of my own insulin response but then sanity returns and I pass up on the thought.

Kudo’s to you for having the faith in your pancreas, I certainly don’t.

I thought Sir Humphrey like NO.

Wow your pancreas is a champ that is really good. I bet my FF would do worst and she is not diabetic. She refused she says she does not want to know.

I was thinking this, too. A gram of carbohydrates raises my blood sugar by about 0.3 mmol/L (6 mg/dl), so eating 75g of carbs without insulin would put my blood sugar at about 25 mmol/L (450 mg/dl), and that wouldn’t come down over time unless I did a correction bolus.

A test like this might be useful to find out how much a gram of carbohydrates raises blood sugar, though, but maybe with a much smaller amount of carbohydrates (maybe 10g?). But otherwise I don’t really see how a test like this is useful, especially for people taking medications or insulin.

Yea, it’s more accurate to test how much a gram raises BG by taking a very small amount of fast acting glucose. I did this using 1 gram glucose to know how to correct lows without overdoing it.

If you are really “insulin dependent” then stopping insulin for two days could easily put you into DKA, which is life-threatening. I definitely wouldn’t do that!

Good lord no, sanity returns and it’s a crazy idea . . .I haven’t that kind of courage.

However I’ve read that some T1’s and insulin dependent T2’s may still have a natural insulin response although it would have to pretty pitiful to require insulin daily. It’s that information that I’d probably be testing, stopping insulin would be bad enough, doing an OGTT would porbably be a failure although I know from past experience that BG’s in the 400 and 500’s are tolerable, however rest assured I’m neither curious or courageous enough to try.

Yes, there are studies that show that a small number (less than 20%) of long-term type 1s have a detectable amount of insulin production, but “detectable” just means measurable; it’s still a minimal amount and not enough to sustain life.

A majority of “insulin dependent” type 2s are not truly insulin dependent in that they wouldn’t die imminently if insulin was discontinued because they still produce enough on their own, but they use insulin to obtain good BG control. Still, if you’re a type 2 who uses insulin, it’s obviously not a good idea to test this unless you have medical supervision.

not sure about the maple syrup.
try it with lucozade: instant glucose, like the one in the OGTT, so results may comparable, and you can extrapolate accordingly.
However, if you want to use ‘everyday’ carbs. I suppose thats ok too, to see how well you are travelling with everyday foods.

So let me set the record straight. I am no doubt a total “whack job” for doing this. However, I am did not enter this without some knowledge about the situation. I am currently in a “honeymoon” and I know that my carb tolerance has been mostly restored. It has happened before and I could see it happened again. I have done a lot of self testing, I am a fan of Seth Roberts ( and the self testing crowd. Normally, 1 gram of carbs would raise me 2-3 mg/dl, I know this through testing. I also know that usually, I have “no” phase 1 response and a “poor” phase 2 response, so attempting the test in my usual condition would have raised me 150-225 mg/dl, bringing my blood sugar to 250-325 mg/dl and it would have remained highly elevated for hours, coming down slowly. I used the “maple syrup” because it is made with corn syrup (mostly glucose syrup), I would have preferred lucozade, I just found it convenient.

I really don’t know why I have these short 2-3 week sessions of being normal. None of my doctors believe me. That is part of why I did this. Last night I treated myself with sushi, I won’t tell you how much, but more than I’ve ever had since diagnosis. And I was back to 84 mg/dl 2 hours after meal. I don’t really understand it. And yes, I have questionable sanity.

ps. My “experiment” was posted in the T2 forum. If you are insulin deficient or believe that these high blood sugars (and they will be high) pose a danger, do not attempt such an experiment. And that does double if you are T1.

I sort of get what you’re saying… I’m so used to having to really gauge my meals so that I’m less than 140 at my peaks… (75 minutes, usually)… and sometimes I fail. Over the last couple of days, however, I’ve been scoring in the 100s-80s. :confused: And I know it’s not my monitor, cus I’ve checked and double checked, and used control solution… and I have a ton of different monitors… I had beans and venison, last night… and generally, I’d be at 130s, pushing 140, at the 75 min mark, and that would be my high… Well, last night, my 75 minute high was 100… and my 2 hour mark was 84! This is a dish that usually gets right up there close to 140 for me. Was the same with lunch… I had a dish with chicken, veggies, and a very small bit of pasta with the veggies – a pasta primavera sort of dish. Usually puts me at 126 mg/dL or so, at 75 minutes… Well, at 75 minutes my blood sugar was 83. I could push it with some kind of test, but I’m just too scared to hurt my pancreas…

I have no idea if this is doing harm. Do you? If my blood sugar returns to normal within two hours, it will clearly only be a transient blood sugar above 140 mg/dl. When I last had one of these, I tried to extend it by eating to Dr. B and keeping a strict regime. But I could not really tell when it ended, and my fasting blood sugar drifted back up anyway. At then end of three months I had no change in my HbA1c.

So, I’m not going to worry about it. The damage by having some short blood sugar spikes for a week or two is probably minimal compared to walking around for years with elevated fasting numbers.

Hey bsc,

I’d like to give this a try sometime but not sure about 75g carbs… I think I also have these honeymoon periods because there are times when I can have a high carb meal (50+ grams) and after 1 hour I am only 117. But then there are times where I have one piece of pumpernickel bread (approx 15g carbs) and I will be 216…

Hmmm… 75g carbs sounds like a lot in the morning…

Do you think because I lost 3 lbs, and gained a lb of muscle, that I improved my control with that? I dunno… I’m at like 65 lbs now, and it didn’t seem to make much difference before.

I would be in the bed next to you Gerri, with an IV and feeling like &%$#@!!! No thank you.

So for a type 2 with a remaining insulin response, you can do this test to understand your tolerance of carbs. The two primary results are to understand whether you still have a phase 1 response which will determine how much of a blood sugar spike you have and then how effective your phase 2 response is, which tells you how many carbs you can eat while still getting back down to target levels at 2 hours.

This test is not the test one should use to determine how much a carbs raise your blood sugar (what I call your carb factor). To do that, with your blood sugar low (and virtually no insulin on board), take a fixed amount of glucose (like 10g) and then measure your blood sugar at 15 and 30 minutes. Subtract the max blood sugar from your starting blood sugar and divide by the number of carbs to determine your carb factor. It is not useful to measure beyond 30 minutes, a simple carb should not continue raising your blood sugar (unless you have digestion troubles, which throws everything off).

You can also estimate your carb factor by dividing your insulin sensitivity factor by your insulin to carb ratio.

ps. And please don’t do this OGTT as a T1, I posted this in the T2 forum and I’m sorry I was not clearer. And just so you know, even I feel a bit sick over 200 mg/dl.