An excess of highs and lows in blood sugar is referred to as “glycemic variability” and can be harmful beyond the presence of highs and lows. The “blood sugar roller coaster” effect itself can possibly damage the heart as well as exacerbate other serious health concerns. It is possible to have a normal HbA1c given that this test represents average blood glucose. A CGM monitor is a useful tool to observe this effect and to make your health care provider aware of the condition.