Lantus and Heat

Because excess heat can activate Lantus post injection, patients are being warned against things such as saunas and hot tubs due to the possibility of severe hypoglycemia.  But I've also seen 'hot showers' included as well.  I've been wondering - how hot is 'hot'?  In the winter I'm always freezing, and a hot shower was great before bed.  I've been hesitant to enjoy such a pleasure since starting Lantus though.  Have any studies been done as to what temperature range can cause problems?  "Hot" to some folks is "Luke Warm" to others, so where is the activation line drawn?

[JDRF-Team-LRS]

Hello Imediject,
We're all volunteers here -- none with medical credentials, so pls review any suggestions you read here with your team.

I've been a pumper since before Lantus came out, so I'm not the best person to address this from personal experience.  In my experience in the past with the older insulins like Ultralente, I typically would learn by trial & error if I had subjected my vial to extremes that were outside its range.  With my pump & tubing, a hot tub is not good so I disconnect.  Since teh tubing has no insulation, even a long hot shower can be trouble, so I disconnect.  Since your insulin is already in your body (98.6 F plus/minus), I would think that a hot shower that doesn't injure your skin would also be tolerated by the Lantus-on-board.

Assuming your ability to feel heat on your skin is not impaired, I would suggest trying a comfy shower and then checking your BGs to see if you notice any degradation.  It's not perfect, but it's practical.  

Maybe otehrs will have more precise suggestions, too.

[Larry68]

Lantus behavior (physicians information) is described here: http://products.sanofi-aventis.us/lantus/lantus.html#Clinical%20Pharmacology

My experience with Lantus led to serious hypoglycemia, but that was due to accidental IV injection of a portion of the dose, which is a documented problem.

Quote from above web page:
"PRECAUTIONS
General:
LANTUS is not intended for intravenous administration. The prolonged duration of activity of insulin glargine is dependent on injection into subcutaneous tissue. Intravenous administration of the usual subcutaneous dose could result in severe hypoglycemia."

This is because the effect described below, of forming microprecipitates below the skin, cannot happen in the blood stream. All the insulin in the blood is available immediately to the body.

Quote from above web page:
"
Pharmacodynamics:
Insulin glargine is a human insulin analog that has been designed to have low aqueous solubility at neutral pH. At pH 4, as in the LANTUS injection solution, it is completely soluble. After injection into the subcutaneous tissue, the acidic solution is neutralized, leading to formation of microprecipitates from which small amounts of insulin glargine are slowly released, resulting in a relatively constant concentration/time profile over 24 hours with no pronounced peak. This profile allows once-daily dosing as a patient's basal insulin."

The concern over heat may be that increase blood flow to the injection site caused by heat affects the rate at which these microprecipitates are absorbed, speeding up the timed release of the insulin to the body.

You may wish to ask if it is heat only to the injection site that causes this problem. IF so, you may be able to direct hot water away from the site, or choose a site that is less likely to be heated. It would also be important to know just what temperature the site needs to be exposed to to affect the rate of insulin release.

Larry