Despite high-end researches that have been going on to find cure for various diseases, medical professionals have not yet found cure for some diseases other than HIV/AIDS which which is globally known to have no cure.
Diabetes is a health condition or rather a disease caused by increased blood sugar levels. The body through the pancreas is supposed to produce a hormone called insulin which regulates the blood sugar level. However, when this fails, blood sugar increases hence this condition.
There are two types. Type1 where the body does not produce enough insulin and Type2 where the body resists insulin. It can only be controlled by living on healthy diet and exercising but there's no cure.
Fully known as poliomyelitis. This condition is caused by a virus known as polio virus. It is common among kids below the age of 5. It affects the nervous system of children causing what is called infantile paralysis.
This might not concern you as an adult but it concerns your children. Ensure they are vaccinated against the virus because once it strikes, there is absolutely no cure.
Arthritis is a condition whereby there is inflammation at the joints causing pain and stiffness. This disease cannot be cured but can be managed once one develops it.
Some medications can be taken to kill the pain but this shouldn't be mistaken to be a cure. It is called remission whereby the symptoms disappear but come back when one ceases to use the medications prescribed.