Anyone with diabetes can tell you how annoying, time consuming and expensive it is to track their sugar levels, but it's crucial for them to live a healthy life. Scientists at MIT and Harvard are developing an ink that once tattooed, changes colors based on gluclose levels. For example, if your levels are low your blue ink will turn brown. The concept can also be applied to sodium and PH levels.
The ink still has a lot of testing to undergo before you can find it at your local tattoo shop, but the response from diabetics has been positive and huge!