Diabetes is a group of metabolic disorders, technically known as Diabetes mellitus, which cause a chronically high level of blood sugar (or hyperglycaemia) because of problems with insulin production or the body not responding to insulin production.
The word diabetes originally derives from the Ancient Greek (through Latin), diabētēs, which means "a passer through", intending like a siphon. It took this name in reference to the excessive urination that is a typical symptom of the disease. The word mellitus, instead, comes from Latin and means "honey-sweetened", because of the sweet characteristic of diabetic urine.
The correct pronunciation of diabetes in English is Dye-uh-bee-teez. It is important to remember that the stress occurs on the -bee part and that the end of the word, -teez, is pronounced with a "z" at the end and not an "s". Diabetes is pronounced in the same way in both American and British English.