When a person loses their ability to regulate their blood sugar, they have diabetes and are at increased risk for heart and kidney disease, loss of vision, and amputations. There are now 422 million adults in the world with diabetes--four times as many as in 1980. Some amazing diabetes data visualizations can be viewed here!
PositiveTip: While the interaction of genes and environment play a role in diabetes, so do physical activity and a healthy diet.