Understand how insulin normally works in the body and what happens when you have diabetes.
Regulate sugar in your bloodstream. The main job of insulin is to keep the level of sugar in the bloodstream within a normal range. After you eat, carbohydrates break down into sugar and enter the bloodstream in the form of glucose, a sugar that serves as a primary source of energy. Normally the pancreas responds by producing insulin, which allows sugar to enter the tissues.
Storage of excess glucose for energy. After you eat — when insulin levels are high — excess glucose is stored in the liver in the form of glycogen. Between meals — when insulin levels are low — the liver releases glycogen into the bloodstream in the form of sugar. This keeps blood sugar levels within a narrow range
If your pancreas secretes little or no insulin (type 1 diabetes) or your body produces too little insulin or has become resistant to insulin’s action (type 2 diabetes), the level of sugar in your bloodstream increases. This is because it’s unable to enter cells. Complete article on how insulin affects blood sugar
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