Insulin is a hormone used to control blood sugar in diabetes. It’s essential for many people with type 1 diabetes and is also used in some people with type 2 diabetes when other therapies aren’t enough.
Key points
- Types of insulin (based on how fast they act and how long they last)
- Rapid-acting: starts working quickly, lasts a few hours (examples: insulin lispro, aspart, glulisine).
- Short-acting (regular): slower start, lasts several hours.
- Intermediate-acting: longer duration, used less often alone nowadays.
- Long-acting: provides a steady level over about 24 hours (examples: glargine, detemir).
- Ultra-long-acting: very flat, lasts over 24 hours (example: degludec).
- Inhaled insulin is also available in some places (used at meals, not for everyone).
- How it’s given
- Subcutaneous injections (most people inject once or twice daily and/or around meals).
- Insulin pens or vials are common; some people use an insulin pump for continuous delivery.
- Many regimens use basal insulin (background) plus bolus insulin at meals (basal-bolus). Some use premixed combos.
- How dosing is determined
- Your doctor or diabetes educator will tailor this to you.
- Basal insulin covers glucose between meals and overnight.
- Bolus insulin is taken at meals to cover carbs and to correct high blood sugar.
- Dosing is adjusted based on blood sugar readings, meals, exercise, and illness.
- Carbohydrate counting and correction factors (how much one unit lowers blood sugar) are common tools.
- Monitoring and targets
- Regular blood sugar checks (often several times a day) and periodic A1c tests.
- A1c target is individual, but many adults aim for roughly under 7% (your provider will personalize this).
- Watch for hypoglycemia (low blood sugar): symptoms include shaky, sweaty, confusion, dizziness. Treat with quick carbs (glucose tablets, juice) and recheck.
- Safety and storage
- Store unopened vials or pens in the fridge; once in use, many pens can stay at room temperature for a limited time.
- Do not reuse needles, rotate injection sites to avoid skin changes, and don’t inject into scarred or inflamed skin.
- Be aware of illness, exercise, or alcohol, which can change insulin needs and risk of hypo/hyperglycemia.
- Common side effects
- Weight gain is possible.
- Injection site reactions or lipodystrophy with repeated injections in the same spot (rotate sites).
- Allergic reactions are rare.
If you’d like, tell me:
- Do you have type 1 or type 2 diabetes, or are you asking generally?
- Are you considering starting insulin, or already using it?
- Do you want a simple overview of basal-bolus vs premixed options, or tips for remembering injections and doses?
I can tailor a more specific explanation or walk you through a typical day-on-insulin plan and safety basics. And if you’re currently managing diabetes and aren’t feeling well or have severe symptoms, seek medical advice or emergency care as appropriate.