Insulin (Hormone) - Role of Insulin in the Body and Effect on Blood Glucose
Insulin
Insulin instructs cells to take in glucose from the blood
Insulin is a hormone  which plays a key role in the regulation of blood glucose levels. A lack of  insulin, or an inability to adequately respond to insulin, can each lead to the  development of the symptoms of diabetes .
In addition to its  role in controlling blood sugar levels, insulin is also involved in the storage  of fat.
The role of insulin in  the body
Insulin is a hormone which plays a number  of roles in the body’s metabolism.
Insulin  regulates how the body uses and stores glucose and fat. Many of the body’s  cells rely on insulin to take glucose from the blood for energy .
Insulin and blood  glucose levels
Insulin helps control blood glucose levels  by signaling the liver and muscle and fat cells to take in glucose from the  blood. Insulin therefore helps cells to take in glucose to be used for energy.
If the body has sufficient energy, insulin signals the liver to take up glucose  and store it as glycogen .
The liver can store up to around 5% of its  mass as glycogen.
Some cells in the body can take glucose  from the blood without insulin, but most cells do require insulin to be  present.
Insulin and type 1  diabetes
In type 1 diabetes ,  the body produces insufficient insulin to regulate blood glucose levels.
Without the presence of insulin, many of the body’s cells cannot take glucose  from the blood and therefore the body uses other sources of energy.
Ketones are  produced by the liver as an alternative source of energy, however, high levels  of the ketones can lead to a dangerous condition called ketoacidosis .
People with type 1  diabetes will need to inject insulin to compensate for their body’s lack of  insulin.
Insulin and type 2  diabetes
Type 2 diabetes is  characterised by the body not responding effectively to insulin. This is termed insulin resistance . As a result the body is less  able to take up glucose from the blood. In the earlier stages of type 2  diabetes, the body responds by producing more insulin than it would normally  need to.
If type 2 diabetes  develops over a number of years, the extra demands on the pancreas to produce  insulin can lead to a loss of insulin producing cells (known as pancreatic beta  cells) as they wear out.
Depending on their level of insulin resistance, people  with type 2 diabetes  may also need to  take insulin injections to manage their blood sugar levels.
Insulin and fat  storage
As well as being  involved in the regulation of blood glucose, insulin is also involved in how  fat is used by the body. When the liver is has  taken up its capacity of glycogen, insulin signals fat cells to take up glucose  to be stored as triglycerides.
An additional effect of insulin is in inhibiting  the breakdown of fats.
Synthetic insulin
People with type 1  diabetes and a proportion of people with type 2 diabetes will need to take  exogenous insulin (insulin that is not produced by one’s own body). Insulin is  usually injected but can also be delivered by an insulin  pump which continually infuses insulin through the day and night.
Synthetic insulin is made in laboratories  and is the most commonly prescribed form of insulin for medication purposes. Non-synthetic animal insulin is also available in the UK if  preferred.
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