The Storage Hormone Insulin Doesn’t Work—Insulin Resistance

Insulin is the body’s only storage hormone, promoting the uptake of glucose and fatty acids into the storage organs adipose tissue and muscle. In the event of acute inflammation or an acute fight or flight response, it is important to switch off the effect of insulin (inducing insulin resistance) so that the now increasingly circulating glucose molecules and fatty acid molecules are supplied to the immune system or the brain/muscles. This evolutionarily conserved program for acute events is also activated in the case of chronic inflammation or chronic stress. In aging humans, insulin resistance is promoted by immobility, overnutrition (too much sugar, too much fat), activation of the stress axes, and slightly increased inflammation in the adipose tissue. Age-related diabetes is the result of this long-term unfavorable development with increasing destruction of insulin production in the pancreas. Nevertheless, insulin resistance is an evolutionarily positively selected mechanism that serves an overactive selfish brain or a highly active selfish immune system.