Insulin Sensitivity, What Makes It Rise and Fall?

My BG levels have dropped so much this summer on days that are especially hot. While the temperatures have been 85 *F or above I have had several lows in the 30-50 (1.7-2.8) range. Adjusting basals and ratios was not helping. Then I remembered reading that insulin sensitivity increases in hot weather. As insulin sensitivity increases, the amount of insulin required decreases. I changed all my sensitivity levels on my pump by increasing them 50%-80%, depending on the time of day… My lows are not as bad now. I think I will have to increase those levels even more.

My research has shown that there several things that increase/decrease insulin sensitivity.

Things that increase insulin sensitivity or increase the absorption rate of insulin:

-Anti-diabetes medications ( Actos, Avandia, Glucophage)

-Losing weight (even 15 pounds can make a difference in insulin sensitivity)

-Excessive amounts of caffein

-Getting adequate rest

-Consuming alohol, especially without eating

-Excercise, especially if you inject into a muscle that will be used a lot

-Bathing too soon after injecting insulin

-Hot weather

-If pumpong, new site not previously used

-Injecting insulin into muscular areas (fatty tissue may require more insulin)

-Exercise can increase insulin sensitivity by as much as 15%, especially in those who are insulin resistant from metabolic disorders including PCOS, thyroid disease, and type 2 diabetes.

Things that decrease insulin sensitivity or decrease the absorption rate of insulin:

-Being overweight

-Being inactive

-Sudden reduction in caffein intake

-Improperly stored insulin can lose its potency

-Certain medications

-Insomnia: sleep deprivation


-Yo-yo dieting and eating disorders

-Diet high in processed carbohydrates and fat

-Certain medical disorders (thyroid, polycystic ovarian syndrome, metabolic syndrome, etc.)

-Certain medical disorders (thyroid, polycystic ovarian syndrome, metabolic syndrome, etc.)

For persons on insulin, additional factors that can make you less sensitive to the effects of insulin include:

-Not rotating injection sites often enough. Repeated insulin injections in the same part of the body can cause lipodystrophy (scar tissue), that can slow absorption of the medication.

-Hyperglycemia (it may take more insulin for a body to respond to a correction bolus when over 300 mg/dL), especially when hyperglycemia is chronic.

-While uncommon, persons with type 1 diabetes can also have a combination that includes type 2 diabetes (double diabetes). This form of combination diabetes calls for the person to take insulin (type 1) but they are resistant to it (type 2) even when taken by injection.

Thank you for this. It’s good information and I learned a few things I wasn’t aware of. This would be a good discussion for all diabetics to read, but especially so for those newly diagnosed or parents of newly diagnosed children.

Lots of good info here Richard…thanks .I use a basal rate for cold weather, below minus 10 Celcius ( my goodness, F ??) , normal weather and hot weather ( over 85 F ) …seems to work for me . Your suggestion to use a different sensitivty level is worth looking at .
I do use less insulin, when I drink decaf capucino in the afternoon , at least fewer spikes , which I may need to correct.( I am a pumper )

Would be an issue for you, but ‘that time of the month’ also causes huge swings in insulin sensitivity.

Very similar to what I did a few years ago. I cut my carbs down to 130g per day and increased my exercise. I lost 34 pounds in 2004. I walk an hour every day and use my treadmill during cold weather.

I need less insulin in hot weather, and more in cold weather. I think a lot of that is due to the difference in my activities at different times of the year.

Here’s list from of drugs that effect BG.