What is Insulin?
Insulin is a hormone that allows the body to use sugar (glucose) for energy. If the pancreas does not produce enough insulin or the body does not use insulin properly, it results in high blood sugar levels (hyperglycemia) and can lead to the development of diabetes.
How is Insulin Produced?
Insulin is secreted by the pancreas, specifically by the beta cells within the pancreas. The secretion of insulin primarily occurs in response to elevated blood glucose levels. In addition to high blood sugar, insulin secretion is stimulated by food intake, elevated levels of fuel molecules in the blood (such as amino acids and fatty acids), and nerve stimulation. Insulin is directly released into the bloodstream, where it performs its function.
Role and Importance of Insulin

What Happens When There Isn’t Enough Insulin?
Without enough insulin, glucose cannot enter your cells and instead accumulates in your blood. This leads to high blood sugar levels and diabetes. A complete lack of insulin over an extended period can lead to a life-threatening complication known as DKA (diabetic ketoacidosis).
There are Two Main Types of Diabetes: Type 1 and Type 2
Type 1 Diabetes is an autoimmune disease where the body cannot properly produce insulin due to damage to the pancreatic cells. The lack of natural insulin is replaced with synthetic insulin. While it can develop in adulthood, it is more commonly diagnosed in young people.
Type 2 Diabetes can occur at any age and is a result of excessive insulin production due to acquired insulin resistance. Over time, this excessive production damages the insulin-producing cells in the pancreas.
Insulin Resistance is another primary cause of diabetes. This occurs when cells in the muscles, fat, and liver do not respond properly to insulin. Prolonged insulin resistance can lead to conditions such as:
- Prediabetes: This occurs when you have elevated blood sugar levels (hyperglycemia) that are not high enough to be classified as diabetes.
- Type 2 Diabetes.
- Gestational Diabetes: This condition can develop during pregnancy. Research suggests that the placenta releases hormones that cause insulin resistance. If your pancreas cannot overcome this resistance, it leads to gestational diabetes, which typically resolves after childbirth.
- MODY (Maturity-Onset Diabetes of the Young) is a genetic form of diabetes, also known as monogenic diabetes, caused by inherited genetic mutations (changes).
Does Insulin Lower or Raise Blood Sugar?
Insulin lowers blood sugar levels. Glucagon (another hormone) naturally raises blood sugar levels. Together, insulin and glucagon work to balance blood sugar levels and keep them within a healthy range.
What Are Normal Insulin Levels?
Every individual is different, and so are their insulin needs. Several factors influence insulin levels:
- The type and amount of food consumed (e.g., carbohydrate-rich foods)
- When and how often you eat
- Level of physical activity
- Whether you are ill or under stress
- Whether you are awake or asleep
- The impact of hormones and medications (e.g., corticosteroids)
Expected morning insulin values after an overnight fast of 12 hours (“fasting”):
Test | Unit | Reference range |
---|---|---|
Insulin | mU/l | 2,60-24,90 |
The recommended range is provided by the test manufacturer, Roche Diagnostics, using the ECLIA method. In practice, in addition to routine testing—measuring blood sugar and insulin levels—a glucose tolerance test (OGTT) is also performed to gain more information about sugar metabolism and insulin resistance.