Understanding Insulin, Glucose, and High Blood Sugar

• When the body digests food, much of it is turned into glucose. Glucose is a sugar that the body’s cells use for energy.
• The hormone insulin helps move glucose into the cells and keeps blood sugar at a healthy level.

When insulin levels are too low or the body cannot use insulin properly, glucose stays in the bloodstream instead of entering the cells. This causes high blood sugar. Over time, high blood sugar can damage the body.

Common Types of Diabetes

Type 1 Diabetes

This occurs when the pancreas (an organ in the body) does not make enough insulin. People with type 1 diabetes must take insulin by injection or use an insulin pump to control blood sugar.

Children and young adults are more likely to develop type 1 diabetes. Less than 10% of older adults with diabetes have this type..

Type 2 Diabetes 

This type occurs when the pancreas does not make enough insulin or when the body does not use insulin properly (this is called insulin resistance).

Older adults are more likely to develop type 2 diabetes because aging can make it harder for the body to process sugar. More than 90% of older adults with diabetes have type 2 diabetes.

Pre-Diabetes and Metabolic Syndrome

These conditions increase the risk of developing diabetes.

• Pre-diabetes means blood sugar levels are higher than normal but not high enough to be diagnosed as diabetes. It increases the risk of developing type 2 diabetes and other health problems, including heart disease.
• Metabolic syndrome refers to a group of conditions, including high blood pressure, abnormal cholesterol levels, high blood sugar, and excess fat around the waist.

You can lower the change of  type 2 diabetes  with a lifestyle that includes a healthy diet, increasing physical activity, getting good sleep and keeping your weight down. This will lower the risk of heart disease and other problems. 

Last Reviewed and Updated: August 2026 
By: AGS/HiAF Public Education Committee, HealthinAging.org Content Reviewers