A method is provided for a portable computing device to read a reaction areaon a teststrip, which is located in a peripheral device placed over an image sensor anda lightsource of the portable computing device. Light is provided with the lightsource, whichthe peripheral device directs to the reaction area. An image including thereaction areais captured with the image sensor. An analyte characteristic is determinedbased on acolor of the captured reaction area in the image.
