4. Gout
Gout is a form of arthritis that causes sharp uric acid crystals to grow within joint tissue. It is incredibly painful, and may also signal prediabetes.
Once considered a disease of kings (Henry VIII was a famous sufferer), gout often occurs due to a rich and overabundant diet. It tends to affect people who are overweight more frequently, and obesity is also a risk factor for prediabetes.