Page changed: Byetta
Added link to new research which appears to explain the effect of the HNF-4a gene defect found in Ashkenazi Jewish and some Nordic populations. I had previously speculated this gene defect might have something to do with the anecdotally reported strong response of people from this population to Byetta.
Common Variants in Maturity-Onset Diabetes of the Young Genes and Future Risk of Type 2 Diabetes Johan Holmkvist et al. Diabetes 57:1738-1744, 2008
It turns out that this particular gene defect turns out to affect hepatic glucose production rather than insulin secretion, which surprised the researchers who ran this study as much as it did me. But it is always good to have a hypothesis checked out by good research.
This means the original speculation that Byetta is helpful to people with gene defect because it raises insulin secretion is wrong. However, there is also evidence that Byetta may be able to suppress this runaway production of glucose by the liver. That may be the explanation of why appears, again anecdotally, to be particularly effective in people who may carry this gene defect.
Here is a study discussing how GLP-1 also glucose production by the liver.
Suppression of glucose production by GLP-1 independent of islet hormones: a novel extrapancreatic effect. Ronald L. Prigeo et al. Am J Physiol Endocrinol Metab 285: E701-E707, 2003.