Blood Sugar Regulation in Diabetics

The human body wants blood glucose (blood sugar Regulation in Diabetics) to stay in a very narrow range. Insulin and glucagon are the hormones that make this happen. Both insulin and glucagon are secreted by the pancreas and are therefore called pancreatic endocrine hormones. The image on the left shows the intimate relationship that insulin and glucagon have with each other. Note that the pancreas is the central player in this schematic. It is the production of insulin and glucagon by the pancreas that ultimately determines whether a patient has diabetes, hypoglycemia, or some other sugar problem.

Insulin Basics: How Insulin Helps Control Blood Glucose Levels

Insulin and glucagon are hormones secreted by islet cells within the pancreas. Both are secreted in response to blood sugar levels but in the opposite way! Insulin is normally secreted by the beta cells (a type of islet cell) of the pancreas. The stimulus for insulin secretion is HIGH blood glucose…simple as that! Although there is always a low level of insulin secreted by the pancreas, the amount secreted into the blood increases as blood glucose rises. Similarly, as blood glucose falls, the amount of insulin secreted by pancreatic islets decreases.

As you can see in the picture, insulin has an effect on various cells, including muscle, red blood cells, and fat cells. In response to insulin, these cells absorb glucose from the blood, which has the net effect of lowering high blood glucose levels to the normal range. Glucagon is secreted by pancreatic islet alpha cells in the same way as insulin… except in the opposite direction. If blood glucose is high, then glucagon is not secreted. However, when blood glucose drops (such as between meals and during exercise) more and more glucagon is secreted. Like insulin, glucagon has an effect on many cells in the body, but most notably the liver.

The Role of Glucagon in Blood Glucose Control

The effect of glucagon is to cause the liver to release the glucose it has stored in its cells into the bloodstream, with the net effect of raising blood glucose. Glucagon also induces the liver (and some other cells such as muscles) to produce glucose from building blocks obtained from other nutrients found in the body (eg, protein). Our bodies want blood glucose to stay between 70 mg/dl and 110 mg/dl (mg/dl means milligrams of glucose in 100 millilitres of blood).

Below 70 is called “hypoglycemia.” Above 110 may be normal if you have eaten within 2 to 3 hours. That’s why your doctor wants to measure your fasting blood glucose… it should be between 70 and 110. However, even after you’ve eaten, your glucose should be below 180. Above 180 is called “hyperglycemia” (which translates to “too much glucose in the blood”). If your 2 blood sugar measurements exceed 200 after drinking a sugar-water drink (glucose tolerance test), then you are diagnosed with diabetes.

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