Blood sugar may be more prone to fluctuation in winter. Diabetes mellitus is a metabolic disease, mainly caused by insufficient insulin secretion or resistance, once the patient develops, then it is easy to have high blood glucose, and need to control blood glucose strictly. And the fluctuation of blood sugar has a certain relationship with the change of seasons. Compared with other seasons, patients may be more prone to blood glucose fluctuation in winter, mainly because of the colder weather in winter, which may stimulate the sympathetic nerves and increase the secretion of adrenaline and other blood glucose-raising hormones in the body, thus triggering the problem of blood glucose elevation. In addition, the patient’s activity level may gradually decrease in winter, which may lead to elevated blood glucose. Once an abnormally high blood glucose level is detected, a medical professional should be consulted for diagnosis and treatment.