You may not have heard of interstitial fluid, but it makes up 14% of your body weight and is a key part of your health. It’s oxygen and nutrient-rich water surrounding your cells, and because it’s so accessible, it’s great for diabetics who can use continuous glucose monitors to check their blood sugar levels. These monitors look like fancy Band-Aids, and contain tiny sensors that sample the interstitial fluid every few minutes for up to a week. This means that diabetics can be warned right away when it’s time for some fruit juice, and make informed decisions about food and exercise without having to finger prick.