glut 2 and glut 5

I am wondering if anyone can help me. I am tring to figure out the relationship with glut 2 and glut 5 and what they would have in common with obesity, gestational diabetes, and type 2 diabetes. I know that they are insulin resistant and I know that your children might be larger when mothers have the gestational diabetes and that the child will be prone to have childhood obesity. But I cannot find the link between glut 2 and 5 in all of this. If anyone can help I would appreciate it. Thanks!!:redbeathe

GLUT2 and GLUT 5 both carry fructose. This and the fact that they are both encoded on the SLC2A gene are the only common element. The relationship is more complex. For absorption GLUT5 carries fructose across the brush border as does GLUT1 for galactose and glucose. GLUT 2 carries all three monosacharides across the Basolateral border into the portal circulation. The best link that I can find is that GLUT5 upregulation can alter GLUT2 metabolism and lead to diabetes. There is some suggestion that the change in the placement of the GLUT5 receptors changes in pregnancy and that if the changes do not occur correctly it may lead to increased gestational diabetes.

Finally there is a lot of literature about fructose and type 2 diabetes. Essentially in a type 2 diabetic GLUT5 levels elevate dramatically and GLUT5 is found in higher concentration in areas where it is normally found in lower concentrations like skeletal muscle. If you treat someone with a medicine such as rosiglitazone the GLUT5 levels decrease.

Best guess is there is a strong link between GLUT5 and DM2 (including gestational diabetes). There is a genetic component but also a dietary component (ie increased DM and obesity can be linked to the increase of high fructose items in the US diet). There is a relationship between GLUT2 and GLUT 5 but since GLUT2 is a passive high affinity transporter its hard to say what particular affect GLUT2 has on diabetes. It may be that a genetic lack of adaptability in GLUT2 makes the effects of a high fructose diet (ie GLUT2 activation) more pronounced.

BTW what kind of class is this? Thats a question I would expect in an upper level molecular genetics class.

David Carpenter, PA-C

I don't know what class the OP is in, but I was surprised by your comment. We learned about Glut 5 and Type II DM in patho for my BS nursing program.

I think that the link between Fructose and DM2 is fairly well established. The link between Glut5 and DM2 is less so. I would say that PCG-1 Beta is probably more the culprit here than GLUT5. There may be some genetic variation behind GLUT5 that predisposes people to DM2 but in all reality its going to be a complex interplay between PCG TNF and some other yet undiscovered genes that lead to diabetes. Also remember most of this is happening in rats and hasn't been proven in humans.

If you are talking about GLUT5 and diabetes (or more properly fructose and diabetes) then yes thats appropriate. However when you are talking about the interaction of GLUT2, GLUT5 with DM2, childhood obesity and gestational diabetes then thats a different and much more complex subject.

David Carpenter, PA-C