More than a million Americans suffer from Type 1 diabetes. The disease occurs when the pancreas mysteriously stops producing insulin, the hormone that converts food into energy. Modern medicine has been able to recreate insulin, but not the finely calibrated delivery mechanism of the pancreas. Now a group of like-minded do-it-yourselfers have gotten together on the internet and—working outside the purview of organized medicine—have figured out how to link a pump, glucose monitor and smartphone to simulate a functioning pancreas. The results have been spectacularly successful.