This study investigated feasibility of a pocket-size scale (named Libra), which provides the mass of the weighed food needed to calculate the grams of carbohydrate intake to be covered by insulin. The scale was designed as a simple and inexpensive measuring device. It is based on a generally available kitchen scale, where a specially designed communication module is added to support Bluetooth communication with a mobile app (named Nutri). The feasibility of the scale was tested by five volunteers, FIT (Flexible Insulin Therapy) diabetes patients from a Slovenian general hospital, who evaluated the scale and the app at home for 21 days. The results of the study proved the simplicity and efficiency of the scale and the app. The system can be easily adapted to suit the needs of patients with other special nutritional needs.