Glucose regulation question(s)

[Aclamity]

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Got two questions for y'all:

1) Trying to figure out how each hormone regulates glucose levels. Here's what I have:
- Glucagon = stimulates gluconeogenesis/lipolysis/proteolysis
- EPI = stimulates gluconeogenesis/lipolysis/proteolysis
- Cortisol = stimulates gluconeogenesis? Inhibits the actions of insulin?
- GH = inhibits the actions of insulin (I think this is what they mean by "diabetogenic," yea?)

2) What's the principle behind using b1-selective beta blockers (as opposed to non-selective) in diabetics? I think I know the answer, but wanted to double check with others.

Thanks

 

[lemonade90]

B2 promotes insulin release. Wouldn't want to block that in a diabetic who need more insulin to achieve the same effects or don't have insulin.

 

[Aclamity]

B2 promotes insulin release. Wouldn't want to block that in a diabetic who need more insulin to achieve the same effects or don't have insulin.

Thanks, that makes perfect sense.

The other reason I heard for this is that lots of people take beta-blockers to avoid the adrenergic effects of a hypoglycemic episode. Since b2 also stimulates gluconeogenesis, b2-blocker would exacerbate a hypoglycemic episode (which diabetics are at risk for because they can easily take too much insulin). Anyone know if this is a reason as well or if I'm just talking out of my butt?

 

[ijn]

I think the major worry is that beta blockers (both selective and non selective) mask the early symptoms of hypoglycemia. You should be feeling tremors, tachycardia, etc. when your blood sugar levels are on the low side. If that's severely blunted or entirely prevented, then you don't know that you should go eat something until your glucose levels are severely depleted.

 

[AndyRSC]

Gluconeogenesis wouldn't exacerbate hypoglycemia; quite the opposite. You may be thinking of glycogenolysis. Epinephrine may also worsen ketoacidosis by stalling TCA and pushing FA towards ketones.

Perhaps you've also heard that beta-blockers also mask the adrenergic effects that foreshadow hypoglycemia, which is another reason to use beta-blockers judiciously in diabetics.

 

[Aclamity]

I think the major worry is that beta blockers (both selective and non selective) mask the early symptoms of hypoglycemia. You should be feeling tremors, tachycardia, etc. when your blood sugar levels are on the low side. If that's severely blunted or entirely prevented, then you don't know that you should go eat something until your glucose levels are severely depleted.

Gluconeogenesis wouldn't exacerbate hypoglycemia; quite the opposite. You may be thinking of glycogenolysis. Epinephrine may also worsen ketoacidosis by stalling TCA and pushing FA towards ketones.

Perhaps you've also heard that beta-blockers also mask the adrenergic effects that foreshadow hypoglycemia, which is another reason to use beta-blockers judiciously in diabetics.

Thanks, guys, all makes sense. I guess those hypoglycemic symptoms are favorable in that they alert the patient that there's not enough glucose around.

Can anyone confirm my facts about GH (that it doesn't stimulate gluconeogenesis, but simply blocks the effects of insulin)? Thanks a lot