By concentration. These work by taking a sample of blood (0.3-1ul), and spread on a test strip containing chemicals that react with the glucose in the blood (glucose oxidase or glucose dehydrogenase). After about 3 seconds, the value is displayed in mg/dl or mmol/l. There are many models with many features, llike a clock and memory.
Chromtatography. The lancets usually get a drop of blood that is then analyzed inside the meter for glucose content.
Depends on the meter. There are all sorts of ways and machines to check blood sugar. Unfortunately they all still require blood. But they can attach to iphones, upload to the internet or even the cloud, use sites other than the fingertips at times the blood sugar is not changing rapidly. Some can check ketones as well as sugar. Some can even provide output to pumps. When in doubt ask your provider and read the manual. Read more...