Because a person with type 1 diabetes no longer has insulin-producing cells in their body, they will either need to inject insulin everyday, or use a pump that delivers insulin under the skin via a cannula (small tube).

How is the insulin made?

The insulin used by type 1 diabetics is made in 3 different ways:

• Animal – made from animal sources like pork or beef
• Human – not from humans but made in a lab to match human insulin
• Analogue – made in a lab to have the same effect as insulin, but designed to work at different speeds.

Human or analogue insulins are more commonly used.

Which insulin regimen is right for you?

In a non-diabetic person insulin is released from the pancreas to help control their blood glucose level. For diabetic people, taking insulin several times a day via injections or a pump aims to imitate the normal pattern of insulin production from the pancreas as closely as possible. There are many types of insulin available but their basic difference is in how quickly they take effect and how often they need to be injected.

Different insulin regimens:

• Two injections a day
• Basal/bolus injections, which can be on fixed doses or flexible dose-adjustment
• Pump therapy.

All these regimens have the same basic aim: to make sure your body has enough insulin to balance the sugar in your blood, so your blood sugar doesn’t get too high or go too low. Your blood sugar rises when you eat foods with carbohydrates in, such as bread, pasta, rice, most fruits, and anything with sugar in it such as sweets, cake, biscuits, or sugary drinks. Your liver also stores sugars and will release them into the blood during the day.

Two injections a day

Some people use a mixed insulin that only needs to be injected twice a day. The insulin is a fixed amount that peaks at particular times, so people on this regimen have to eat set amounts of carbohydrate at fixed times, sometimes including snacks between meals, and cannot miss a meal. Very few people are put on this regimen nowadays, but some of the people interviewed on this site use this style of treatment.

Basal/bolus injections

Most people who inject insulin are on a basal/bolus regimen. Basal insulin is longer-acting, while bolus insulin is shorter-acting.

Basal insulin is designed to work slowly rather than peak, and it lasts in the body between 4 and 12 hours, sometimes up to 30 hours or more. Examples include Lantus (glargine), Levemir (detemir) and Tresiba (degludec), Hypurin Bovine Lente and Hypurin Bovine PZI. This insulin is injected once or twice a day, depending on how long it lasts in your body, and covers the sugars released slowly by the liver.

Bolus insulin acts faster, peaks quickly, and doesn’t last as long in your body. It is only injected when you want to eat something with carbohydrate in it, to match the sugars that the food will release in your blood. Short-acting bolus insulins start acting after 15–30 minutes, have a peak action of 2–6 hours and can last for up to 8 hours. Examples include: Humulin S, Velosulin, and Hypurin neutral.

Rapid-acting bolus insulins start to act right away and have a peak action of 0–3 hours. They tend to last around 2–5 hours. Examples include Humalog (lispro) and Novorapid (aspart)

Fixed doses

Some people on basal/bolus regimens eat the same amount of carbohydrate at every meal, and inject a set amount of bolus insulin to match it each time. The amount of basal insulin is also usually the same each day. Some of the people interviewed on this site used this regimen, several relying on their healthcare team to make adjustments to the insulin dose.

Flexible dose-adjustment

Increasingly, people on basal/bolus regimens manage their own insulin doses and adapt them to whatever they want to eat. On a flexible dose-adjustment regimen, as long as you learn the ratio of how much insulin you need per 10g of carbohydrate, you can eat as much or as little carbohydrate as you like, and use the ratio to work out how much bolus insulin you need. You can also learn how to work out what basal dose is best for you and how to change it. People on flexible dose adjustment regimens change their insulin doses themselves to fit their lives and their choice of food.

A separate page explains the use of insulin pumps for dosing insulin.