​Type 1 diabetes (T1D) is usually diagnosed in children and young adults and affects just 5% of all individuals with diabetes. However, it may also present in older adults.

In type 1 diabetes, the body is unable to produce insulin. The body breaks down the sugars and starches into simple sugar known as glucose which is required for energy. Insulin is the hormone that allows glucose to enter into various parts of the body from the bloodstream.

“Whilst type 1 diabetes is irreversible, with insulin replacement, individuals may learn to manage their condition, and live long healthy lives,” says Dr Daphne Su-Lyn Gardner, Consultant, Department of Endocrinology, Singapore General Hospital, a member of the SingHealth group.

Glucose and insulin

Glucose (The Body’s Fuel)

Glucose is a type of sugar that the body uses for energy required to perform body functions. Glucose is present in our bodies at all times, even while sleeping, since all cells need glucose for energy.

Without diabetes, glucose levels are kept very tightly between 4-6.5 mmol/l. However, once diabetes develops, it becomes very difficult to keep glucose levels within this range whilst avoiding frequent hypoglycaemia (low blood glucose).

Glucose comes largely from carbohydrates (simple sugar and starches). Upon absorption from the digestive tract into the blood stream, it moves into the interstitial fluid and eventually into cells. Glucose that is not used immediately for energy is stored in the liver. Importantly, for glucose to move into the cells, insulin is required.


Insulin is a hormone produced by the pancreas. Even in those without diabetes, there is a constant supply of insulin produced so that glucose may enter into the cells. When insulin is not available, glucose stays in the blood and interstitial fluid.

Without diabetes, the pancreas produces insulin almost continuously, and in response to the amount of glucose in the blood. This is so precise that exactly the right amount of insulin is produced to keep blood glucose (BG) levels in a tight range. During sleep or in between meals, small amounts of insulin is produced every few minutes for small amounts of glucose (basal insulin) 24 hours of the day. During meal times, larger amounts of insulin are produced in response to larger amounts of glucose (bolus insulin) Please see figure below.​

Insulin production over 24 hours, during the fasting state (basal insulin) and in response to food intake (bolus insulin).​

​​​​​​​​​What Is Type 1 Diabetes?

In those with type 1 diabetes, there are thus 2 components to insulin replacement: the basal insulin dose and the bolus insulin dose. Basal (or background) insulin provides the constant supply of insulin between mealtime and during sleep while the bolus insulin is used to cover the post-meal glucose rise following ingestion of carbohydrates at mealtime.

Individuals with type 1 diabetes ought to be on a basal-bolus regimen with quick acting insulin delivered in multiple doses throughout the day. Please refer to the section on insulin for the types of basal and quick acting insulins available.

Another mode of delivery of insulin is through continuous subcutaneous insulin infusion via an insulin pump. Please refer to the article on ​ insulin pumps​ for more information about this.​​

Read on to learn about the guide to self-management for​ type 1 diabetes​.

Ref: O17​​