This is a 24-week, open-label, randomized, multi-center trial conducted in three tertiary hospitals. There are three follow-up measures; at baseline, post-intervention at Week 12, and Week 24. Subjects are diagnosed as type 1 DM, type 2 DM, and/or post-transplant DM, and initiate or currently use insulin therapy. After the given education on insulin dose titration and prevention for hypoglycemia and 1 week of run-in period, subjects are randomized in a 1:1 ratio to either the ICT-based intervention group or the conventional intervention group. Subjects in conventional intervention group will save and send their health information to the server via the PHR app, whereas those in ICT-based intervention group have additional algorithm-based feedback messages. The health information includes levels of blood glucose, insulin dose, details on hypoglycemia, food diary, and number of steps. The primary outcome will be the proportion of patients who reach an optimal insulin dose within 12 weeks of enrolling in the study without severe hypoglycemia or unscheduled clinic visits.