mellitus, or diabetes, is an illness in which there is
an abnormally high level of glucose in the blood. Depending on how high glucose level is and how long it has
been high, one may feel fairly well, or one may be so sick that require hospitalization. Usually, doctor will
test for diabetes if one has symptoms such as thirst, frequent urination, weight loss, blurred vision, and
Glucose and its Uses in the body
Glucose is asugar and is one of the energy sources of the body. Some
organs in our bodies, such as the brain, are particularly dependent upon glucose as an energy source, so it is
very important that the body maintain the amount of glucose in the blood in the normal range: if the level is
too high or too low, there are serious consequences. To avoid these consequences, the body has a complex set of
mechanisms to keep the glucose in the normal range.
The liver is in charge of taking up and releasing glucose into the
bloodstream. After a meal, the blood carrying nutrients from digestion first ﬂows through the liver, which
removes the excess glucose. When the glucose level in the blood drops (for example, after fasting or
exercising), the liver does the opposite and releases glucose into the bloodstream. The liver knows how to
regulate the level of glucose in the blood because it receives signals from hormones, which are chemical
messengers in the blood. The two hormones that are particularly important in diabetes are insulin and
hormones are produced in the islets of Langerhans of the pancreas, an elongated organ located behind and below
the stomach in the abdomen. There are about a million islets in a normal pancreas, and they consist of several
types of cells— the beta cells make insulin and the alpha cells make glucagons.
In a person with diabetes, the beta cells in the islets fail, and this
alters the balance of insulin and glucagon actions on the tissues. The cause and degree of beta cell failure
varies in different kinds of diabetes,
the hormone that ensures that the glucose entering the bloodstream from the digestion of food is removed from
the blood. It does this by switching the body’s metabolism so that it uses glucose instead of fat for its energy
needs. Insulin also signals the body to make glycogen (a storage form of glucose) and to use glucose to make
triglycerides (another important energy source) for storage in fat cells. Insulin does all this by its effects
on liver cells, muscle cells, and fat cells
In the liver, insulin makes the
liver cells convert glucose into glycogen, a storage form of glucose, and make triglycerides, a storage
form of fat.
In the muscles,
insulin allows the glucose transport into the muscle cells.
In the fat
tissues, insulin stops the breakdown of triglycerides and release of fatty acids into the
Glucagon acts in an opposite manner to insulin: it switches the body’s
metabolism so that it uses fatty acids instead of glucose as its energy source, and it signals the body to
increase glucose production. Glucagon achieves this by instructing the liver cells to break down glycogen and
release glucose into the bloodstream. It also signals the fat tissues to break down triglycerides and release
glycerol and fatty acids into the blood.
Thus, it is the balance of insulin and glucagon that regulates the glucose
levels in the blood during the fed and fasting states.