Recycle the original cap that your insulin pen was issued with and replace it with the Timesulin cap after your next injection. Ensure you hear an audible 'click' so that you'll know that your Timesulin cap is fitted into place and won't fall off in your pocket / handbag / briefcase.

Once clicked into place, Timesulin will start counting time, showing you how long ago you last administered your insulin shot.

Timesulin will only reset when it has been off the insulin pen for more than 8 seconds, which allows you to do a quick check on insulin levels on your way out to dinner, for example, without resetting the timer