My brush with diabetes: Zero-calorie sweeteners and insulin resistance

Over the past few years, I've thought of myself as taking decent care of my body. I went from looking like that, in February 2006, to looking like this, in May 2013:

denis, February 2006denis, May 2013

The way I did this was through (1) some aerobic exercise, mainly at first, to get some initial weight down; (2) weight lifting, to develop muscle mass; and (3) a rigorous application of my diet, high in protein, restricted in calories, but not otherwise restricted in content.

Imagine my surprise, then, when I recently had a full blood test done - the first one in probably 15 years - and the results for my glucose and insulin were these:
Insulin:  150.5 uUI/mL (reference range: 2.0 - 27.0)
Glycemia: 155 mg/dL    (reference range: 60 - 100)
Glucose:  8.61 mmol/L  (reference range: 3.3 - 5.5)
HOMA-IR:  57.59
I hadn't been fasting when this blood sample was taken; an hour before the sample, I had eaten a breakfast of 410 kCal and 36 g of protein, the rest mostly carbs.

The doctor knew this, and he still assured me, these results were far from normal. A blood glucose level of 155 mg/dL, at any time, is dangerously close to Type 2 Diabetes Mellitus. According to the Wikipedia article on Gestational diabetes - which is different, but similar - "When a plasma glucose level is found to be higher than 126 mg/dl (7.0 mmol/l) after fasting, or over 200 mg/dl (11.1 mmol/l) on any occasion, and if this is confirmed on a subsequent day, the diagnosis of GDM is made, and no further testing is required."

But look at how I look! I eat, like, 7 measured meals a day. How could this be?

Two theories:
  • Although my diet had been strict about protein and calorie content, and for the most part I had fewer than 3 hours between meals, my diet was extremely liberal in artificial sweeteners. I had them everywhere. In protein bars, which were my go-to convenience food. In protein powder. In my morning cereal. And most of all, in my Coke Zero. I loved Coke Zero and Diet Coke, and I had recently been drinking as much as 3 liters of that per day. A recent study found that artificial sweeteners are associated with Type 2 Diabetes.
  • Lack of aerobic exercise. Even though I was in good shape, my exercise mostly consisted of body weight exercises, such as push-ups, pull-ups and squats. Prolonged exercise counters insulin resistance, and I wasn't doing enough.
So the doctor did what he could - prescribed me metformin, which lowers blood glucose - and I also did what I could; removed all artificial sweeteners from my diet, and started using the treadmill for 45 minutes a day, most every day. Two weeks later, I did a proper fasting for 10 hours before the blood test, and the results were as follows:
Insulin:  6.00 uUI/mL (reference range: 2.0 - 27.0)
Glycemia: 77 mg/dL    (reference range: 60 - 100)
Glucose:  4.27 mmol/L (reference range: 3.3 - 5.5)
HOMA-IR:  1.13
All normal! So I'm not going to be diabetic for now, after all.

Still, in addition to the exercise, and avoiding aspartame and sucralose, this was after 2 weeks of metformin. Since my insulin and glucose are both decent now, my doctor and I decided to try without metformin, but keep the lifestyle changes. We'll see what happens in another test, in about 3 weeks.

The role of zero-calorie sweeteners

Given my experience, my theory on zero-calorie sweeteners is this. When you eat something that tastes sweet, your pancreas releases insulin in expectation of a spike in glucose. But it just so happens that you had a zero-calorie drink sweetened with aspartame or sucralose, so your body isn't getting any glucose. Instead, you only get flooded with insulin. The big insulin spike causes the cells in your body to consume the glucose in your blood, and now: (1) you feel hungry, having burned through available glucose; and (2) since there's now all this insulin and no glucose, your cells develop a measure of insulin resistance.

I had been doing this to myself a lot. I liked to drink a Coke Zero or Pepsi Light after a meal, to "help with digestion". I did this because I felt heavy after a meal if I didn't, but refreshed if I did; perhaps the reason I felt refreshed was the insulin spike causing the body to absorb glucose. But shortly after I drank the Coke, I felt hungry: perhaps, all the insulin had caused my glucose to go low. Because it still wasn't time to eat, I had another drink, and then another. I had been spiking my blood insulin level, without ingesting calories my body was expecting. So I developed insulin resistance, and this showed up in the test.

Since I cut all zero-calorie sweeteners from my diet, I've found that following the diet has been easier. I now get hungry at the right time, instead of all the time.

If you are trying to lose weight, my current recommendation would be to avoid all foods with zero-calorie sweeteners. They may look appealing, but they'll just make you hungrier. And as the latest studies suggest, they may lead to Type II Diabetes, even independent of weight loss.


I posted a follow-up on this topic on December 30, 2013.

A study published in 2014 found zero-calorie sweeteners cause diabetes through changes in gut flora.


vasectomy said...

Why don't you just get a blood sugar tester and give it a try. Have a test, eat a ton (metric not imperial) artificial sweeteners, and test again. If your theory was right there should be a significant impact.
Actually the effect you describe does exist, yet humans aren't affected. If dogs ingest Xylitol their blood sugar drops which is incredibly dangerous for them. On the other hand I've actually eaten a lot of Xylitol without dying or even feeling any adverse effects.

denis bider said...

vasectomy: Why don't you just get a blood sugar tester and give it a try. Have a test, eat a ton (metric not imperial) artificial sweeteners, and test again. If your theory was right there should be a significant impact.

That wouldn't show an insulin spike directly, unless the blood sugar tester also shows insulin levels.

vasectomy: On the other hand I've actually eaten a lot of Xylitol without dying or even feeling any adverse effects.

Xylitol is not a zero-calorie sweetener - it tastes as sweet as table sugar, but has about 2/3 as many calories.

Nevertheless - you're right that if there was a large insulin spike after consuming artificial sweeteners, and this spike was large enough to deplete glucose in the blood, I should be collapsing after drinking 3 Diet Cokes.

This blog post states convincingly that aspartame and sucralose are not associated with insulin spikes, while acesulfame K and saccharin could be, but there's no compelling evidence.

According to this other post on the same site, insulin resistance in liver and muscle tissue develops like this:

"if the liver and muscle cells are already filled with glycogen, those cells start to become resistant to the call of insulin. The insulin “receptor sites” on the surface of those cells start to decrease in number as well as in efficiency. The term is called “down regulation.” Since the glucose can’t get into the muscle or liver cells, it remains in the bloodstream. Now the pancreas senses there’s still too much toxic glucose in the blood, so it frantically pumps out even more insulin, which causes the insulin receptors on the surface of those cells to become even more resistant, because excess insulin is also toxic! Eventually, the insulin helps the glucose finds it way into your fat cells, where it is stored as fat."

If I should trust this author, it could be that my apparent insulin resistance was not caused by zero-calorie sweeteners, but could have developed due to insufficient exercise. If my liver and muscle tissue was constantly full on glycogen, then insulin resistance could have developed as a result.

denis bider said...

Then again, this other article finds exactly the opposite:

"Contrary to all expectation, the aspartame breakfast induced a similar rise in glucose and insulin levels at baseline than the sucrose meal, even if the aspartame meal had the same taste, and was 22 percent lower in calories and 10 percent lower in carbohydrates, with an inferior glycemic index."

The evidence so far appears to be contradictory...