Diabetes and Insulin
Newly Diagnosed | What is Diabetes? | Diabetes and Insulin | Classification of Diabetes | Diagnosis of Diabetes | Managing Diabetes | Blood Glucose Levels and HbA1c
Insulin is the key (literally!) to diabetes. Insulin is a hormone produced by the beta-cells in the pancreas. Insulin enables the body to take glucose out of the blood and use it for energy. If we don’t make enough insulin and/or the insulin doesn’t work properly, the glucose stays in our blood, our body is deprived of it’s energy source, the blood glucose level rises and diabetes results.
All of the various types of diabetes are related to a problem with insulin.
Regulation of Blood Glucose levels
One of the most important roles of insulin is to help with the regulation of blood glucose levels and it does this through a number of complex metabolic pathways.
Insulin enables cells in the liver, muscle, and fat tissue to take glucose from the blood and use it for energy, or convert it to glycogen that can be stored and used later.
Insulin also prevents the utilization of fat as an energy source. In absence of insulin or in conditions where insulin is low glucose is not taken up by body cells, and the body begins to use fat as its energy source.
Insulin Production
Insulin secretion is controlled by blood glucose levels. Other stimuli like sight and taste of food, nerve stimulation and increased blood concentrations of other fuel molecules, including amino acids and fatty acids, also promote insulin secretion.
[Glucose is the breakdown product from the digestion of carbs. Amino acids are the breakdown products from the digestion of protein. Fatty acids are the breakdown products from the digestion of fats]
Insulin production is controlled by the insulin gene. When insulin is first made it is in the inert form of ‘pre-proinsulin’. Pre-proinsulin is broken down to proinsulin, and then this is cleaved to release insulin and another protein molecule called C-peptide.
C-peptide can be measured in the blood, and provides a good indication of insulin production [see Lab Tests]
Insulin Action
Insulin works just like a key in a lock. When the insulin molecule docks at it’s receptor on the cell wall, the gate opens to allow glucose to enter the cell.
We call it insulin resistance when this lock and key mechanism doesn’t work properly; this is one of the main features of Type 2 diabetes [see page on Insulin Resistance in section on Type 2 Diabetes].
Insulin Therapy for Diabetes
Insulin is a protein and would be destroyed by our digestive enzymes if taken by mouth. It therefore has to either be injected or continuously infused into the body via a needle or cannula.
Insulin is manufactured using ‘recombinant DNA’ technology. This involves placing the human insulin gene into either bacteria (or yeast), cultivating the bacteria (or yeast) and then harvesting the insulin that is made by the bacteria (or yeast).
Small variations in the formulation have given rise to a number of different types of insulin, each with different characteristics [see Different insulins].
Page updated Jan 2025
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Newly Diagnosed | What is Diabetes? | Diabetes and Insulin | Classification of Diabetes | Diagnosis of Diabetes | Managing Diabetes | Blood Glucose Levels and HbA1c