Due to aging development，the improvement of living standards，the increase in work pressure，and other reasons，the incidence of diabetes mellitus has increased year by year，and the prevention and treatment of diabetes mellitus have become the focus and difficulty of clinical treatment.Based on the physiological characteristics of the heart and long-term clinical experience，Professor LIN Lan explained the pathogenesis of diabetes mellitus from the perspective of the heart and believed that the disease was caused by depression of the heart Qi.Heart fire is not reduced but transformed into fire toxin，causing sugar toxicity and promoting the progress of the disease.Heart Yang deficiency leads to phlegm and blood stasis and complications.In the treatment，it is necessary to take the heart as the starting point，follow the three steps of “regulating mind”“regulating Qi”，and “regulating body”，and flexibly use the methods of moistening and calming the mind，nourishing the essence and mind，replenishing Qi and nourishing the heart，invigorating the heart and Qi，activating blood circulation and resolving phlegm，etc.，which provides new ideas and new methods for the treatment of diabetes mellitus with traditional Chinese medicine.