Sunday, May 12, 2019

Retrospective #86: Beta Cell Function and Insulin Sensitivity

In early 2013 I made an appointment with an endocrinologist to find out what was going on with my glucose metabolism. I was interested in my % Beta cell function and my % Insulin Sensitivity (and its reciprocal, Insulin Resistance). I had read about a HOMA Assessment test that determines those values, and I wanted to be tested.
I hadn’t been to see an endo in 25 years. In that first visit, he had me go to the out-patient department of a local hospital for a 4-hour oral glucose tolerance test (OGTT). That test confirmed the diagnosis that had been made a few years earlier that I was a Type 2 diabetic. After seeing the test results, he increased my dose for a sulfonylurea (SU), the only oral diabetes medication in use in the U.S. at that time.
It would be another 5 years (in 1995) before another doctor added Metformin, which by then was permitted here. But before long I was maxed out on both the SU and Metformin and was starting on a 3rd class, a TZD (Avandia).
Then, in 2002, to lose weight (NOT to treat my diabetes) my doctor suggested I try the Atkins Induction diet. He had just read the Gary Taubes NYT Magazine cover story, “What If is All Been a Big Fat Lie?”  The first day on Atkins Induction (20 grams of carbs a day), I had a hypo. I called my doctor, and he told me to stop the Avandia. The next day when I had another, he cut the SU and Metformin dosages in half, and then soon thereafter, in half again.
I lost 60 pounds on Atkins Induction, but after a few years, I gained back 12. I then decided to try the Bernstein diet for diabetics. In the next year I lost another 100 pounds and eventually another 22 for a total loss of 170 pounds.
Along the way, I weaned myself off the sulfonylurea, but I still took 500mg Metformin once a day. But, all told, I figured I had been on a sulfonylurea, which pushes the pancreas to secrete more insulin in response to a glucose challenge, for almost 20 years. Referencing Dr. Ralph DeFronzo’s Banting Lecture at the 2008 ADA Annual Convention, I feared I had already lost 80% of my Beta cell function by the time I was diagnosed in 1986!
At the end of the introduction to the full paper published in the ADA magazine, “Diabetes,” Dr. DeFronzo also said, “Sulfonylureas are not recommended because, after an initial improvement in glycemic control, they are associated with a progressive rise in A1C and progressive loss of β-cell function” (emphasis added by me).
Given my history on sulfonylureas and Dr. DeFronzo’s prognostications, I was surprised with the HOMA Assessment test results: Beta Cell function = 68.2%; Sensitivity = 94.6%; and IR = 1.1 (1.057). Has anyone else out there had a HOMA assessment? The nurse who placed the test order said she had been working with this doctor for 10 years and he had never ordered the test before.
The endo told me the test was mostly used in research. Okay, but, I wondered, if not commonly used in clinical practice, does the test have clinical value? What can be learned from it? My first read is that I am not as bad off as I thought I was. True, I have been eating Very Low Carb “on and off” for over 10 years, and for the last four months, “totally on.”  My last HbA1C was 5.7, down from recent low 6s. I had been eating a Very Low Carb “ketogenic” diet, recently about 1,200kcal/day, without hunger. That is because my body is ketoadapted and in ketosis virtually all the time. My body is in homeostatic balance and happy with my dietary intake, my supplements, and with the fatty acids, glycerol and ketone bodies it makes from my body fat that it is breaking down every day for energy.
My daily FBG readings are almost always under 100, and my weekly averages about 90mg/dL. I work hard to keep them under 100. I am very careful to eat Very Low Carb (VLC) and to never eat too much protein.
So, what does my HOMA assessment test reveal? Is my Type 2 diabetes in “clinical remission” because of the way I eat? Has my diet “reversed” my Type 2 diabetes, “normalized” my Beta Cell function and improved my insulin sensitivity? Did my Beta Cells regenerate themselves after years of being depleted?
I hope to learn the answers to these questions from my new endo in my follow-up appointments. I can hardly wait.

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