Stevia is a genus of several species of herbs and shrubs from the sunflower family. Stevia is low glycemic, low carbohydrate, it doesn't spike your insulin levels and a safer alternative than sugar for people suffering from obesity and high blood pressure. Be warned stevia is about 10 to 15 times as sweet as sugar in the powder form and 200-300 times and sweet as table sugar in refined extract form.
Stevia does not seem to have any of sugars unhealthy drawbacks.
There are virtually no calories in stevia making it perfect for your dietary needs whether you are trying to lose weight or perhaps a diabetic (consult your doctor for all diabetic concerns). Stevia does not promote tooth decay in fact two tests conducted by Purdue University's Dental Science Group concluded that stevia may actually help prevent cavities.
Stevia can be used in cooking and or baking but it will not caramelize so keep that in mind. With all this being considered stevia seems to be not only a viable and healthy sugar substitute but perhaps the only one that makes much sense at this time. Do your research and judge for yourself. I recommend the green kind the less processing involved the better. You can most likely find green stevia rebaudiana in your local health food store.