The blood testing may check for any health issues you have, including high cholesterol, high protein levels, diabetes or other health conditions.
In addition, your blood may be checked for any STD's including AIDS/HIV.
Also, your blood may be tested for prescription drugs and illegal drugs; such as, marijuana, cocaine and methamphetamine, among others.
The life insurance company uses the lab result findings to help determine your current and future health, your life expectancy, and if they should insure you for life insurance, and at what rate.
However, there are life insurance companies that offer life insurance with no blood tests required.