Health Tips

Diabetes, also known as diabetes mellitus, is a disease characterized by raised levels of blood sugar due to problems with insulin in the body. Insulin is a hormone that helps sugar move from the blood and get into the innumerable cells of your body to provide energy.

When insulin becomes defective or deficient or both, sugar remains trapped in the blood, leading to raised blood sugar levels. Persistently high levels of blood sugar tend to damage almost all organs of the body and, over time, may lead to such dreadful complications as blindness, kidney failure, amputation, heart attack, and stroke.

Blood Sugar Mechanism: Basic Facts

Your body needs energy to live, grow, and function. Glucose, which is a form of sugar, is the main nutrient that provides this energy. Carbohydrates (sugars and starches in your meals) are the principal source of glucose.

When you eat carbohydrate-containing foods, they break down into their simple sugars in the digestive tract, and are absorbed as glucose (sugar) into the bloodstream.

To provide energy, sugar should go inside the cells and muscles of the body. However, sugar by itself cannot enter the cells and needs help. This help is provided by insulin, which helps sugar get into the cells where it is used as a fuel for energy.

Insulin Secretion

Insulin, which is secreted by the pancreas, is the key player in blood sugar mechanism of the body. The pancreas is an organ situated below and behind your stomach.

A normal pancreas contains about 1 million cells called the islets of Langerhans. These cells are found in clusters in the pancreas. Each islet contains four types of cells in which two types, alpha and beta cells, are especially significant in regulating blood sugar. Beta cells secrete insulin, whereas alpha cells secrete another hormone called glucagon (read more about it in Prevent, Treat and Self Manage Diabetes and Related Complications).

Insulin, as just noted, is the most important agent in blood sugar control. The pancreas secretes insulin in two modes:

Insulin secreted in response to meals. After you eat food, the pancreas in a parallel action, releases a matching amount of insulin that helps sugar move from the blood and enter into billions of cells throughout your body.

This way blood sugar is maintained at normal levels. When you eat excess food, sugar is generated in a greater amount than your body immediately needs. In such situations, insulin helps excess sugar to be stored as a reserve in the liver and muscles of the body in the form of glycogen.

Your body uses stored sugar reserves (glycogen) as a quick source of energy when you are not eating and sugar is not entering your circulation. In addition, insulin helps store a part of excess sugar in the form of fat in the body.

The other mode of insulin secretion is called basal secretion. In this mode, the pancreas continuously secretes insulin in very small amounts.

In this mode:

– Insulin suppresses the production of sugar by the liver, thereby helping control blood sugar. (The liver produces sugar in two ways: by breaking down its sugar reserves, and by producing more sugar through a process called gluconeogenesis.)

– Insulin delivers sugar to the brain cells continuously in very small amounts. (Continuous supply of blood sugar is essential for functioning of the brain.)

Glucagon Secretion

Unlike insulin that lowers blood sugar, glucagon (secreted by alpha cells) raises blood sugar levels. Glucagon stimulates the liver to convert its glycogen reserves into sugar and release it into the bloodstream when:

A) Your blood sugar is falling

B) You need extra energy such as while you are exercising

C) You are fasting or between the meals (when sugar is not entering your circulation)

Glucagon secretion in the above situations helps prevent low blood sugar. However, most people with type 1 diabetes, within 5 years of having this disease, tend to develop a defect in which glucagon does not respond to and fails to offset falling blood sugar.

Such a condition exposes these people to high risks associated with low blood sugar levels.
The mechanisms of insulin secretion, insulin action, and glucagon secretion all are well tuned and balanced when you are healthy.

In normal health when you eat food, beta cells secrete the right amount of insulin to process sugar, which is absorbed from your meals. The insulin so released moves sugar fast from the blood and delivers it effectively to the cells of your body.

This makes blood sugar return quickly to its normal range. On the other hand, secretion of glucagon prevents low blood sugar. In the presence of well regulated blood sugar mechanism in normal health, sugar circulating in the blood is neither high nor low but remains within the normal range of 60 to less than 100 mg/dL (3.3 to less than 5.6 mmol/L).

Measuring Blood Sugar

Blood sugar is measured in mg/dL (milligrams of sugar per deciliter of blood) or mmol/L (millimoles of sugar per liter of blood). In some countries, including the United States, the common practice is to express blood sugar in mg/dL; in other countries it is expressed in mmol/L. To convert mg/dL values into mmol/L, divide the mg/dL value by 18. By this calculation, a blood sugar value of 126 mg/dL will be equal to 7 mmol/L.