Blood glucose monitoring reveals individual patterns of blood glucose changes, and helps in the planning of meals, activities, and at what time of day to take medications. Also, testing allows for quick response to high blood sugar (hyperglycemia) or low blood sugar (hypoglycemia). This might include diet adjustments, exercise, and insulin dose. Measuring HbA1c is the primary method of assessing long-term glycemic control, and for most patients checking HbA1c every three months or so is enough. However, the HbA1c cannot measure glucose level variability or detect hypoglycemia so checking blood glucose is necessary, and self-monitoring of blood glucose should be done before meals, at bedtime, if there are signs and symptoms of hypoglycemia, before exercising, and in some other situations. This may require checking blood glucose by fingerstick 6-10 times a day, and the need for such frequent blood glucose checks can be reduced by use of a continuous glucose monitoring device (CGM). Continuous glucose monitoring devices can provide better glycemic control (decreased HbA1c) than self-monitoring, their use can reduce the incidence of hypoglycemic events, and these advantages are especially strong for patients who have frequent episodes of hypoglycemia and/or hypoglycemic unawareness. The use of a CGM, however, does not mean that patients never need to check blood glucose.