A study published in this month's Diabetes Care is titled in a way that makes it sound like Byetta "improves beta cell function."
But if you read even the abstract you will see that "improving beta cell function" is NOT the same as rejuvenating beta cells--the claim that the drug manufacturer has been making for Byetta ever since it was released. In fact, what this study proves is the exact opposite: . While Byetta causes more insulin to be secreted in people who are taking the drug, this effect ends as soon as the drug is discontinued.
Here's the study:
One-Year Treatment With Exenatide Improves β-Cell Function, Compared With Insulin Glargine, in Metformin-Treated Type 2 Diabetic Patients. A randomized, controlled trial Mathijs C. Bunck. Diabetes Care 32:762-768, 2009
What they did here was this:
Sixty-nine metformin-treated patients with type 2 diabetes were randomly assigned to exenatide (n = 36) or insulin glargine (n = 33). β-Cell function was measured during an arginine-stimulated hyperglycemic clamp at week 0, at week 52, and after a 4-week off-drug period.What they found was:
Treatment-induced change in combined glucose- and arginine-stimulated C-peptide secretion was 2.46-fold (95% CI 2.09–2.90, P < 0.0001) greater after a 52-week exenatide treatment compared with insulin glargine treatment. Both exenatide and insulin glargine reduced A1C similarly: –0.8 ± 0.1 and –0.7 ± 0.2%, respectively (P = 0.55). Exenatide reduced body weight compared with insulin glargine (difference –4.6 kg, P < 0.0001).
This means A1c didn't change on average in people using Byetta compared to those using Lantus., though they were secreting more insulin. However, on average, weight decreased significantly in the Byetta group compared to the Lantus group.
But here's the kicker:
β-Cell function measures returned to pretreatment values in both groups after a 4-week off-drug period. A1C and body weight rose to pretreatment values 12 weeks after discontinuation of either exenatide or insulin glargine therapy.
After a year of use, once people stopped taking Byetta their beta cell function went right back to what it had been. Obviously, had their beta cells been rejuvenated, we would have expected to see improved insulin production even without the Byetta. And as most of us would have predicted, losing weight doesn't appear to have changed their ability to control their blood sugars either.
There's an important point to keep in mind here. If you'll remember, and earlier study showed that averages are very misleading when evaluating Byetta's performance. Byetta works very well for about 1/3 of those who take it and barely at all in the rest. You can read about that study HERE.
Dctors have been prescribing Byetta to people who do not experience significant weight loss or improved blood sugar control because they believe it is rejuvenating their beta cells. This claim was based on test tube and rodent studies and has never been confirmed by any human studies. All human studies, like this one, evaluate "beta cell function" simply by seeing how much insulin the beta cell is pumping out in response to a stimulus. Byetta, like the sulfonylurea drugs, does improve the beta cell's ability to secrete insulin, while Byetta is in the system.
But this new study should make it clear that if you aren't one of the lucky people who respond to Byetta with dramatic improvements in blood sugar and weight loss, there is no reason to keep taking it.
Still, over the past two years I have heard from friends who have tried Byetta and have experienced near "miracle weight loss" and dramatic decreases in their need for injected insulin even when eating meals with up to 40 or 50 grams of carb. Some of these are people who required insulin even while eating low carb diets.
So my feeling about Byetta is that it is well worth a trial. Give it two months. If you don't see weight loss and significant improvement in your blood sugars, there is no reason to continue with it.
What disturbs me is how many people I hear from whose doctors insist they continue Byetta when their blood sugar deteriorates while taking it and they don't see weight loss. If that's your situation, you will want to use insulin instead.
It's also worth noting that while Byetta is not officially approved for people using insulin, I have heard from quite a few people who are using that combination successfully. If you combine the two you will probably need to lower your insulin dose other wise hypos are likely.
It's also worth noting that the mechanism by which Byetta was supposed to be rejuvenating beta cells is the same mechanism used by the other incretin drug, Januvia, for which the identical claim is being made. This new study suggests that Januvia is not regenerating beta cells either.