A study appeared in the journal Cell last week that the authors are touting as a revelation of the “widely recognized” link between consumption of a high-fat diet and development of type II diabetes. (Click here to see the scientific paper).
A quick glance at just the abstract of this article is all it takes to realize that it is an extremely technical paper dealing with basically the reduced lifespan of a certain glucose transporter on the mouse pancreatic beta cell membrane as a function of a high-fat diet:
Pancreatic ÃŽ² cell-surface expression of glucose transporter 2 (Glut-2) is essential for glucose-stimulated insulin secretion, thereby controlling blood glucose homeostasis in response to dietary intake. We show that the murine GlcNAcT-IVa glycosyltransferase is required for Glut-2 residency on the ÃŽ² cell surface by constructing a cell-type- and glycoprotein-specific N-glycan ligand for pancreatic lectin receptors. Loss of GlcNAcT-IVa, or the addition of glycan-ligand mimetics, attenuates Glut-2 cell-surface half-life, provoking endocytosis with redistribution into endosomes and lysosomes. The ensuing impairment of glucose-stimulated insulin secretion leads to metabolic dysfunction diagnostic of type 2 diabetes. Remarkably, the induction of diabetes by chronic ingestion of a high-fat diet is associated with reduced GlcNAcT-IV expression and attenuated Glut-2 glycosylation coincident with Glut-2 endocytosis. We infer that ÃŽ² cell glucose-transporter glycosylation mediates a link between diet and insulin production that typically suppresses the pathogenesis of type 2 diabetes.
I have known a lot of medical reporters, and none of them in their daily scans of the medical literature would have picked up this article to report on. In fact, I’m quite sure that their eyes would have quickly glazed over had any even tried to read it. So how did it get picked up?
Either the journal or the authors themselves issued a press release proclaiming this great discovery. Few, if any, medical reporters could understand this article or its supposed significance, so they relied on the authors to tell them what it meant. These reporters then parroted the authors claims to the world without really having a clue themselves as to what it was all about.
So, it’s the authors here who are at fault for all this blather; not the poor medical reporters.
And the authors are quite excited about their work:
“Our findings suggest that the current human epidemic in type 2 diabetes may be a result of GnT-4a enzyme deficiency,” said Dr Jamey Marth, UCSD professor of cellular and molecular medicine.
“The GnT-4a enzyme is required to synthesize a glycan structure that holds the glucose transporter in place at the beta cell surface. The loss of this key transporter is directly linked to reduced GnT-4a protein glycosylation, a high-fat diet, and type 2 diabetes,” he added.
He then gushes:
“If you could somehow stimulate production of this enzyme, you might be able to render animals, and perhaps humans, resistant to high-fat diet-induced diabetes.”
Discounting the fact that mice aren’t simply fuzzy miniature people and don’t respond the same to diet or much of anything else as we do (which means this study has little, if any, human relevance), I’m reminded by that last statement of one of my favorite scenes in one of my favorite movies.
About two third of the way through Butch Cassidy and the Sundance Kid there is a scene in which Butch and Sundance, who have been hired to keep an old miner’s payroll safe, are arguing over where each thinks the bandits will strike from as they ride down the mountain to pick up the payroll. The old miner, played wonderfully by Strother Martin, asks them what they are going on about. They tell him that they are looking for the outlaws they’ve been hired to ward off. The old miner spits a glob of tobacco juice and fixes them with a stare. He says,
Morons. I’ve got morons on my team. Nobody is going to rob us going down the mountain. We have got no money going down the mountain. When we have got the money, on the way back, then you can sweat.
I feel kind of the same way about the idea that this is some kind of exciting study showing definitively how high-fat diets lead to type II diabetes.
I want to say,
Morons. I’ve got morons on my team. Nobody gets diabetes from eating fat when no one eats fat anymore. Diabetes is skyrocketing while people are eating less fat than they ever have in history. If and when the fat consumption curve mirrors the diabetes curve instead of going in the opposite direction, well, then you can sweat.
* Butch to Sundance.