Educational guide — not medical advice. We sell nothing and dispense no medication. For anything about your own care, talk to a licensed clinician or pharmacist. In an emergency, call your local emergency number. Full disclaimer.
Simple Insulin CareDiabetes education guide
For anyone newly diagnosed — and those who love them

Insulin, explained simply and kindly

A diabetes diagnosis can feel like a lot all at once. Take a breath. By the end of this page you'll actually understand what insulin is, how you'll use it, and how to stay safe — in plain language, with no medical background needed.

How to use this guide: read straight through, or jump to what you need — you don't have to read it all, and you don't have to memorize anything. It will be here when you come back.

Start with the big picture Jump to staying safe
A person calmly checking a blood glucose meter at home, with an insulin pen and a glass of water nearby
Start here

The big picture, in four calm steps

Before any of the detail, here is the whole story in four steps. If you only read this part, you'll still have the shape of it. Everything below simply fills these in.

  1. 1

    Insulin replaces what your body can't make on its own

    Insulin is a natural hormone. In diabetes your body can't make enough of it, or can't use it well. Taking insulin simply puts back what's missing so your body can use food for energy.

  2. 2

    You balance "background" and "mealtime" insulin

    Most routines use a steady background dose that works all day, plus a little extra at meals. That's really the core idea — two jobs, working together.

  3. 3

    You check your levels so you can see what's happening

    A quick finger-prick or a small wearable sensor turns blood sugar from invisible into a number you can see, learn from, and share with your care team.

  4. 4

    You stay safe, and you get it from licensed care

    You'll learn the few signs that matter and what to do about them — and you'll always get insulin through a real clinician, prescription and pharmacy. That's it. That's the map.

Millions of people live full lives with insulin. It feels like a lot today; it becomes routine. You've got this — and you're not doing it alone.

Part 1 · The basics
Illustration of an insulin pen and vial beside a body cell taking in glucose

What does insulin actually do?

Short answer: insulin is the "key" that lets sugar from your food move out of your blood and into your cells, where it's used for energy. In diabetes that key is missing or not working — so you add it back.

Insulin is a hormone made by the beta cells of the pancreas. It works like a key that lets glucose (sugar) move from the bloodstream into cells, where it is used for energy.

After you eat, carbohydrates raise the glucose level in your blood. In response, the pancreas releases insulin, which helps cells take up that glucose and lowers blood sugar back toward a normal range. Your body also keeps a small, steady amount of insulin working in the background between meals and overnight.

You'll hear two words a lot, so let's make them simple:

  • Basal = the steady background insulin that works all day and night.
  • Bolus = the mealtime insulin, a larger amount around food.

In diabetes, this system breaks down: the body either cannot make enough insulin, cannot use it effectively, or both. Glucose then builds up in the blood instead of fueling cells. Insulin therapy replaces or supplements the body's own insulin so glucose can be used and blood-sugar levels stay closer to target.

Remember this

You don't need the biology. The takeaway is simply: insulin lets your body use food for energy, and you'll be replacing what's missing — a background amount, plus a bit at meals.

Want the longer version? Read the full Understanding Insulin page →

What kind of diabetes is this?

Short answer: "diabetes" isn't one thing. The three common kinds differ in why they happen and how they're usually managed — but all of them mean blood sugar runs higher than it should.

Knowing which type you (or your loved one) have helps the rest of this page make sense. Your clinician will tell you which one applies — here's the plain version of each.

Often needs insulin to live

Type 1

An autoimmune condition where the immune system damages the insulin-making cells of the pancreas. People with type 1 produce little or no insulin and need insulin therapy to live. It often appears in childhood or early adulthood, but can begin at any age.

Most common

Type 2

The body still makes insulin but becomes resistant to it, and over time may not make enough. It's influenced by genetics together with lifestyle factors. Management may involve lifestyle changes, oral medicines and, for some people, insulin.

Begins in pregnancy

Gestational

High blood glucose first identified during pregnancy. It usually resolves after birth but raises the future risk of type 2 diabetes. It's managed closely with an obstetric and diabetes care team.

A gentle note: symptoms such as unusual thirst, frequent urination, unexplained weight change or persistent fatigue are worth discussing with a clinician. Only a healthcare professional can diagnose diabetes.

What are the types of insulin?

Short answer: you don't need to memorize this. The gist: some insulins are "background" (basal) and work slowly all day; some are "mealtime" (bolus) and work fast around food. Your prescriber picks which ones are right for you.

Insulins are grouped by how fast they start working (onset), when their effect is strongest (peak), and how long they last (duration). The table below is here if you're curious or want to look something up later — skim it, don't study it. The ranges are general and combine figures from major authorities; individual products differ.

An insulin pen, a vial and a syringe arranged on a clean surface
Type (and its job)Starts workingStrongestLastsCommon examples (generic — brand)
Rapid-actingMealtime / bolus ~15 min~1–3 h~3–5 h lispro (Humalog), aspart (NovoLog), glulisine (Apidra); faster versions: Fiasp, Lyumjev
Short-acting (Regular)Mealtime ~30–60 min~2–4 h~5–8 h Regular human insulin (Humulin R, Novolin R)
Intermediate (NPH)Background ~1–4 h~4–12 h~12–24 h NPH / isophane (Humulin N, Novolin N)
Long-acting (basal)Background ~1–4 hLittle or no peakUp to ~24 h glargine U-100 (Lantus, Basaglar), detemir (Levemir)
Ultra-long-actingBackground ~1–6 hNo pronounced peak~36 h or longer glargine U-300 (Toujeo), degludec (Tresiba)
Premixed / combinationBackground + mealtime ~5–60 minVaries by mix~10–16 h 70/30, 75/25, 50/50 (Humulin 70/30, NovoLog Mix 70/30, Humalog Mix 75/25)
InhaledMealtime ~10–15 min~30 min~2–3 h human insulin inhalation powder (Afrezza)
In plain terms: the top rows are fast, mealtime insulins; the middle rows are slow, background insulins; premixed combines both. Ranges are general and educational, drawn from the American Diabetes Association, CDC, NIDDK and Cleveland Clinic; sources sometimes differ, so a span is shown. Exact onset, peak, duration and dosing for any specific product come from its label and your prescriber. This is not dosing guidance.

How a typical day fits together

Here's the part that actually matters. Many people use a long- or ultra-long-acting insulin once or twice a day for steady background (basal) coverage, plus a rapid- or short-acting insulin at meals (bolus). Premixed insulins combine both in fixed ratios. Inhaled insulin covers mealtimes only and, in type 1 diabetes, must be paired with a long-acting insulin. The right combination is highly individual — your care team builds it around your life.

"You don't have to learn all of this at once. A little at a time, it becomes second nature."

Part 2 · Using insulin, day to day
Three insulin delivery devices: a vial with syringe, an insulin pen and an insulin pump

How do you actually take insulin?

Short answer: not as a pill — your stomach would destroy it. Instead it goes in just under the skin, most often with an easy pen, sometimes a vial and syringe, a wearable pump, or even an inhaled form. Pens are what many people start with.

Insulin cannot be taken as a pill — it would be broken down by digestion — so it is delivered in other ways. Each method has trade-offs in convenience, cost and flexibility. The right choice is made with your care team; here's a friendly tour of the options.

Insulin pen

A pre-filled or refillable pen with a fine needle; you dial the dose and inject. This is the option many people find easiest to start with.

  • Portable, discreet and easy to dose accurately.
  • Usually costs more than vials; not made for every insulin.
  • A new pen needle is used and the pen primed each time.

Vial and syringe

Insulin is drawn from a vial into a syringe and injected under the skin — the long-standing, reliable method.

  • Lowest cost; widely available; simple and reliable.
  • Works with essentially every insulin type.
  • Less discreet; requires drawing up each dose.

Insulin pump

A wearable device delivers a steady flow of rapid-acting insulin (basal) plus mealtime doses (bolus) through a small cannula under the skin. Many pumps now link with a CGM in automated insulin delivery (AID) / hybrid closed-loop systems that auto-adjust background insulin.

  • Fine-tuned dosing, fewer injections, flexible meals/activity.
  • Higher cost, training, constant wear.
  • If delivery is interrupted, blood sugar can rise quickly and DKA can develop — a reason to monitor closely.

Inhaled insulin

A rapid-acting powder (Afrezza) breathed in at the start of a meal; covers mealtimes only and is paired with a long-acting insulin in type 1 diabetes.

  • Needle-free mealtime option with a fast onset.
  • Not for people who smoke or who have asthma or COPD; lung-function testing is required.
  • Cough is a common side effect.

A quick word on where it goes — and rotating spots

This is general background only, not a how-to for dosing. Your specific technique, needle length and plan should be learned in person from a clinician or diabetes educator.

Where insulin is injected

Insulin is given into the fat layer just under the skin (subcutaneously), not into muscle or a vein. Common sites are the abdomen (often the fastest, most consistent absorption), thighs, upper/outer arms, and buttocks. Absorption speed can differ between sites.

Why you rotate sites

Using the same spot repeatedly can cause lipohypertrophy — lumps or fatty deposits under the skin — which makes insulin absorb unpredictably. Rotating between areas, and within an area while spacing injections, helps keep absorption consistent. Using the same general area at the same time of day can give more comparable results.

About CGMs and "closed-loop" pumps

A continuous glucose monitor can feed readings to a compatible pump so the system nudges insulin up or down automatically. Even so, hybrid closed-loop systems still need you to enter meals/carbohydrates. These technologies are powerful, but they're set up and adjusted with a diabetes care team — not something to figure out alone.

How do you know your numbers?

Short answer: a quick finger-prick meter gives you a number right now; a small wearable sensor (CGM) shows the trend over the day. There's no single "right" number for everyone — your clinician sets the targets that fit you.

Checking turns blood glucose from something invisible into a trend you can see and discuss. Day-to-day numbers and longer-term measures together give a fuller picture than any single reading.

A person holding a blood glucose meter, with a continuous glucose monitor sensor on the upper arm

Finger-prick meter (BGM)

A blood glucose meter gives a single value from a drop of blood at one moment — useful around meals, activity, or when you feel symptoms. It's a precise snapshot, but doesn't show direction or what happens between checks.

Continuous glucose monitor (CGM)

A CGM uses a small sensor under the skin to read glucose in the fluid between cells, updating roughly every few minutes and showing trends and direction with alerts. Because it reads that fluid rather than blood, readings can lag, so occasional finger-prick checks are still advised. Common systems include Dexcom and FreeStyle Libre.

What numbers are people usually aiming for?

There's no single "normal" number that fits everyone. The figures below are commonly cited general targets for many non-pregnant adults with diabetes. Think of them as a reference point, not a rule — your clinician sets the ranges that are right for you based on your age, type of diabetes, other conditions and pregnancy.

When you checkCommon general targetApprox. mmol/L
Fasting / before a meal80–130 mg/dL~4.4–7.2
1–2 hours after start of a mealBelow 180 mg/dL~<10.0
A1C (3-month average) — many adultsOften below 7%eAG ~154 mg/dL at 7%
 In plain terms: these are general targets for many adults — not your personal numbers. General targets are cited by the American Diabetes Association and CDC; yours are individualized by your care team. The A1C-to-estimated-average-glucose (eAG) mapping is from the ADA.

What's "A1C"? (you'll hear it a lot)

A1C is one blood test that estimates your average blood sugar over about the last three months — a "big picture" number to go with your daily checks.

The A1C test (also written HbA1c) estimates your average blood glucose over roughly the previous three months. The ADA publishes a conversion from A1C to an estimated average glucose (eAG) so the percentage is easier to relate to day-to-day readings.

A1CeAG (mg/dL)eAG (mmol/L)
6%1267.0
7%1548.6
8%18310.1
9%21211.8
10%24013.4
 In plain terms: a higher A1C means a higher average glucose. This is the ADA A1C / eAG conversion.
Optional: the numbers clinicians use to diagnose diabetes

These thresholds are used by clinicians to diagnose prediabetes and diabetes. They are diagnostic cut-offs, not personal treatment targets, and a diagnosis is always made by a healthcare professional, usually with repeat or confirmatory testing.

TestNormalPrediabetesDiabetes
A1CBelow 5.7%5.7–6.4%6.5% or above
Fasting plasma glucose99 mg/dL or below100–125 mg/dL126 mg/dL or above
Oral glucose tolerance (2-hr)139 mg/dL or below140–199 mg/dL200 mg/dL or above
 Diagnostic criteria as published by NIDDK / NIH. Diagnosis is made by a clinician.
Insulin pens and vials stored on the door shelf of a refrigerator

How do you store insulin?

Short answer: keep spare insulin in the fridge (not the freezer), keep the pen or vial you're using at room temperature, and never let it freeze or bake in a hot car. When in doubt, check the leaflet that came with it.

Insulin is a protein and loses potency if it gets too hot, freezes, or is kept in use too long. Storing it correctly keeps it working as intended. Always follow the instructions on your specific product's label, because details vary by insulin.

Spare (unopened) insulin
Keep refrigerated, typically about 36–46°F (2–8°C), until the printed expiration date. Store away from the freezer compartment and not in the fridge door.
The one you're using
Many insulins may be kept at room temperature (commonly up to about 86°F / 30°C) for a limited number of days. The number of in-use days varies by product — for example roughly 28 days (e.g. Lantus, many vials), 42 days (e.g. Levemir), or 56 days (e.g. Tresiba, Toujeo). Check the package insert.
Never freeze it
Frozen insulin can break down and should be thrown away, even after it thaws.
Keep it out of heat & sun
Keep away from direct heat and sunlight; don't leave insulin in a hot car. Both reduce potency.
When you travel
Carry insulin in your carry-on, not checked luggage. Keep it cool but not resting directly on ice or a frozen pack; keep the prescription label with it.
Give it a look first
Don't use insulin that is discolored, clumped, frosted, or has particles. Clear insulins should look clear; NPH (cloudy) should be gently mixed until uniformly cloudy.

In-use day counts above are examples and differ by product; the product label and your pharmacist are the authority. General guidance aligns with the FDA, ADA and manufacturer labeling.

Part 3 · Staying safe

What if my blood sugar drops too low — or runs too high?

Short answer: a low comes on fast (shaky, sweaty, hungry) — eat fast sugar right away. A high builds slowly (thirsty, tired, peeing a lot). They're treated in opposite ways, and a few situations are true emergencies — all spelled out below.

This is the most practical section on the page, so take your time with it. Recognizing the difference between a low (hypoglycemia) and a high (hyperglycemia) matters, because they're treated in opposite ways. Severe lows and diabetic ketoacidosis (DKA) are emergencies — we'll make those crystal clear.

A glass of orange juice, glucose tablets and a clock, illustrating treating a low blood sugar

Low Hypoglycemia — comes on fast

Often treated as low at 70 mg/dL (3.9 mmol/L) or below; below 54 mg/dL (3.0 mmol/L) is a more serious low.

What it can feel like

  • Shaking, sweating, fast or pounding heartbeat
  • Hunger, dizziness or light-headedness
  • Anxiety, irritability or confusion
  • Blurred vision, trouble concentrating, weakness
  • Severe: trouble walking/seeing, seizures, passing out

High Hyperglycemia — builds slowly

Symptoms often appear once glucose rises above roughly 180–200 mg/dL and build over hours to days.

What it can feel like

  • Increased thirst and frequent urination
  • Fatigue or tiredness
  • Blurred vision
  • Headache, weakness (later)
  • Persistently high readings on your meter or CGM

If you're low: the "rule of 15", in four simple steps

For a person who's awake and can swallow safely: have about 15 grams of fast sugar, wait 15 minutes, check again. That's it — eat, wait, recheck.

A widely taught approach for a conscious person who can swallow safely: if blood sugar is 70 mg/dL or below, take about 15 grams of fast-acting carbohydrate, wait 15 minutes, and recheck. If still low, repeat. Once back in range, eat a meal or snack if the next meal is more than an hour away.

  1. Step 1

    Confirm a low (about 70 mg/dL or below).

  2. Step 2

    Take ~15 g fast carbs: glucose tablets, 4 oz (½ cup) juice or regular soda, 1 Tbsp honey/sugar, or hard candy per label.

  3. Step 3

    Wait 15 minutes — don't pile on more food yet.

  4. Step 4

    Recheck. If still low, repeat. Then eat a meal/snack if needed.

A balanced healthy plate with vegetables and grains beside a water bottle and walking shoes

What about everyday life — food, exercise, sick days?

Short answer: carbs raise blood sugar the most, exercise usually lowers it, and being unwell can push it up. You don't change everything overnight — you learn these patterns with your care team over time.

Three everyday topics that influence blood sugar. These are general concepts to discuss with your care team, not a personalized plan — and none of them mean your life has to shrink.

Food & carb counting

Carbohydrates have the biggest short-term effect on blood sugar. Carb counting means tracking the grams of carbohydrate in food and drink; people on mealtime insulin use it to help match insulin to meals. As a rough rule, about 15 grams of carbohydrate equals one "carb choice."

Exercise & glucose

Physical activity generally lowers blood glucose and can improve how the body uses insulin. It may cause lows during or after activity, so many people check before and after. If blood sugar is high (for example 240 mg/dL or above) with ketones present, sources advise not exercising until that is addressed.

Sick-day basics

Illness can raise blood sugar. General sick-day guidance is to keep taking insulin (don't stop without advice), check blood sugar more often (often every few hours), drink fluids to stay hydrated, check for ketones, and know when to call your clinician or seek care if you can't keep fluids down.

Part 4 · The cost question & getting it safely

What about the cost of insulin?

Short answer: cost is a real worry, and there's real help — a $35/month cap for many in the US, manufacturer assistance programs, savings cards, and lower-cost biosimilars. If money is tight, talk to your care team before ever skipping a dose.

Affording insulin is a real concern for many people — you're not alone in worrying about it. Several programs and product options can lower the price. Coverage rules differ by insurance and location, so confirm the details for your own situation — and never skip or ration insulin without talking to a clinician first.

The $35/month cap

In the United States, the Inflation Reduction Act capped out-of-pocket insulin at $35 per month for Medicare Part D enrollees, effective 2023, and removed the deductible for insulin.

Separately, the major makers Eli Lilly, Novo Nordisk and Sanofi voluntarily capped or cut prices toward $35/month for many products in 2023–2024. How (and whether) a cap applies can depend on your insurance and the specific product.

Patient-assistance & savings

Manufacturer programs can reduce out-of-pocket cost — sometimes to little or nothing — for people who qualify, typically by income:

  • Lilly Cares (Eli Lilly)
  • NovoCare (Novo Nordisk)
  • Sanofi Patient Connection

Manufacturer copay savings cards and pharmacy discount tools (such as GoodRx) may also help.

Biosimilars & follow-ons

Lower-cost alternatives to brand insulins exist. Some are approved as interchangeable biosimilars, meaning a pharmacy may substitute them under applicable law:

  • Semglee and Rezvoglar — interchangeable with the long-acting insulin glargine product Lantus
  • Basaglar, Admelog — earlier "follow-on" insulins

A pharmacist can explain which options are available where you live.

Cost figures and programs change and vary by country and plan. Use this as a starting point and verify current details with your pharmacist, insurer, or the program directly. If cost is a barrier, ask your care team about options rather than skipping or rationing insulin.

How do you get insulin the safe, right way?

Short answer: through licensed care — a real clinician, a valid prescription, and a licensed pharmacy. If a website offers insulin with "no prescription needed," that's a red flag, not a shortcut. Walk away.

Insulin is a prescription medicine in most countries for good reason. A safe path always runs through licensed professionals — never through an anonymous website that skips the prescription.

1

See a licensed clinician

A doctor or qualified prescriber evaluates your situation, confirms a diagnosis and decides whether insulin or another treatment is appropriate.

2

Get a valid prescription

A real prescription specifies the exact product, strength and instructions for you. Any site offering "insulin without a prescription" is a warning sign, not a convenience.

3

Use a licensed pharmacy

Fill prescriptions at a pharmacy that is licensed in your jurisdiction and that asks for that prescription. A licensed pharmacist can answer questions about storage and use.

4

Verify online pharmacies

If buying online, confirm the pharmacy is accredited — for example through a national regulator or a recognised verification programme such as NABP / .pharmacy in the United States.

How to spot an unlicensed online pharmacy

Anonymous sites that sell insulin or weight-loss medication without a prescription put your health and money at risk. Learn the red flags and how to check that a pharmacy is real and licensed.

See the warning signs
  • Requires a valid prescription before dispensing.
  • Shows a verifiable licence and physical address.
  • Has a licensed pharmacist you can contact.
  • Is accredited by a recognised regulator or programme.

"This felt like a mountain on day one. Give it a little time — the steps become routine, and life keeps being life."

You're not doing this alone
Keep for later · Reference

Glossary, common questions & sources

You don't need to read this now. It's here for whenever a word is unfamiliar, a question comes up, or you want to see where the information comes from. Tap any item to open it.

Glossary — plain-language definitions the words you'll hear
A1C (HbA1c)
A blood test estimating average glucose over about three months. Often expressed as a percentage; many adults aim below 7% (individualized).
Basal insulin
Background insulin that works steadily between meals and overnight (long- or ultra-long-acting).
Bolus insulin
Mealtime or correction insulin (rapid- or short-acting) taken to cover food or bring down a high.
Beta cells
The cells in the pancreas that make insulin.
BGM
Blood glucose meter — a fingerstick device giving a single glucose reading.
CGM
Continuous glucose monitor — a wearable sensor that tracks glucose trends throughout the day.
Carb counting
Tracking grams of carbohydrate in food; about 15 g equals one "carb choice."
DKA
Diabetic ketoacidosis — a dangerous build-up of ketones from too little insulin. A medical emergency.
eAG
Estimated average glucose — A1C translated into an average mg/dL or mmol/L figure.
Glucagon
A hormone/medicine (injection or nasal) that raises blood sugar; used for severe lows.
Hyperglycemia
High blood sugar.
Hypoglycemia
Low blood sugar, commonly treated at 70 mg/dL or below.
Insulin resistance
When cells respond poorly to insulin, central to type 2 diabetes.
Lipohypertrophy
Lumps or fatty deposits from repeated injections in one spot; rotating sites helps prevent it.
NPH
Intermediate-acting insulin (isophane); appears cloudy and is gently mixed before use.
Onset / peak / duration
When an insulin starts working, when its effect is strongest, and how long it lasts.
Subcutaneous
Into the fat layer just under the skin — where insulin is injected.
Titration
Gradually adjusting a dose under medical guidance to reach target glucose.
Units (U-100)
Insulin is measured in units; U-100 means 100 units per milliliter, the most common concentration.
Biosimilar
A biologic highly similar to an approved reference product; an "interchangeable" one may be substituted at the pharmacy under applicable law.
Frequently asked questions quick, plain answers

Common questions answered in general terms. For anything specific to you, talk to a healthcare professional.

Can I buy insulin online without a prescription?

In most countries insulin is a prescription-only medicine, so a legitimate pharmacy will always ask for a valid prescription. A website offering insulin with no prescription is a strong warning sign of an unlicensed operation. Speak to a clinician about the correct, lawful way to obtain insulin where you live.

What are the main types of insulin?

Insulin is grouped by how quickly and how long it works: rapid-acting and short-acting (Regular) for mealtimes; intermediate-acting (NPH); long-acting and ultra-long-acting for background (basal) coverage; premixed combinations; and inhaled insulin for mealtimes. Exact onset, peak and duration vary by product — see the table above. Your prescriber decides which product and routine fits you.

Is there one "normal" blood sugar number for everyone?

No. Targets are individualized and depend on factors such as age, type of diabetes, other health conditions and pregnancy. A commonly cited general range for many non-pregnant adults is roughly 80–130 mg/dL before meals and below 180 mg/dL one to two hours after the start of a meal, with an A1C often below 7% — but your clinician sets the ranges that are right for you.

What is the difference between type 1 and type 2 diabetes?

In type 1, the body makes little or no insulin and insulin therapy is required to live. In type 2, the body becomes resistant to insulin and may not make enough; it is managed with a range of approaches that can include lifestyle changes, oral medicines and sometimes insulin. A clinician can explain what applies to your case.

What is the "rule of 15" for low blood sugar?

For a conscious person who can swallow safely: if blood sugar is at or below 70 mg/dL, have about 15 grams of fast-acting carbohydrate (such as glucose tablets, 4 oz of juice or regular soda), wait 15 minutes, and recheck — repeat if still low. If a person cannot swallow, is unconscious, or is seizing, that is an emergency: give glucagon if available and trained, and call emergency services.

How should I store insulin, and can I keep it out of the fridge?

Unopened insulin is generally kept refrigerated at about 36–46°F (2–8°C) until its printed expiration date. Once in use, many insulins can be kept at room temperature (commonly up to about 86°F / 30°C) for a limited number of days that varies by product — for example roughly 28, 42, or 56 days — so check the package insert. Never freeze insulin, and keep it out of heat and direct sunlight.

What are the warning signs of DKA, and when should I get emergency help?

Diabetic ketoacidosis is a medical emergency. Signs include very high blood sugar, fruity-smelling breath, nausea and vomiting, stomach pain, fast and deep breathing, dry mouth, and trouble thinking clearly. Seek emergency care if blood sugar stays at or above 300 mg/dL, breath smells fruity, you cannot keep fluids down, you have trouble breathing, or you have several of these signs.

Why is there a $35 cap on insulin, and does it apply to me?

In the United States, the Inflation Reduction Act capped out-of-pocket insulin at $35 per month for Medicare Part D enrollees (effective 2023). Separately, Eli Lilly, Novo Nordisk and Sanofi voluntarily capped or cut prices toward $35 per month for many products in 2023–2024. Whether and how a cap applies depends on your insurance and the specific product, so confirm the details for your situation; savings cards and assistance programs may also help.

What is a biosimilar or "interchangeable" insulin?

A biosimilar is a biologic medicine highly similar to an already-approved reference product, with no clinically meaningful differences. Some are approved as interchangeable — for example Semglee and Rezvoglar are interchangeable with the long-acting glargine product Lantus — which can allow substitution at the pharmacy under applicable law. A pharmacist can explain the options where you live.

Where is insulin injected, and why rotate sites?

Insulin is injected into the fat layer just under the skin (subcutaneously), commonly in the abdomen, thighs, upper arms or buttocks. Rotating sites — and rotating within an area — helps prevent lipohypertrophy (lumps or fatty deposits) and keeps absorption more consistent. Learn specific technique from a clinician or diabetes educator.

Does exercise raise or lower blood sugar?

Activity generally lowers blood glucose and can improve how the body uses insulin, and it may cause lows during or after exercise — so many people check before and after. If blood sugar is high (for example 240 mg/dL or above) with ketones present, sources advise not exercising until that is addressed. Plan activity with your care team.

Is this website a pharmacy, and can it tell me my dose?

No. This is an independent educational resource. It sells nothing, dispenses no medication, is not a pharmacy, and cannot provide a dose or personal medical advice. Decisions about whether to use insulin, which product, and how much must be made with a licensed clinician.

Read the full FAQ page →

Sources & further reading where this comes from

The general figures and explanations on this page reflect guidance from recognised public-health and medical organizations. For decisions about your own care, rely on your clinician and the current guidance from these bodies.

  • American Diabetes Association (ADA)diabetes.org — insulin basics & routines, blood-sugar targets, A1C/eAG, hypoglycemia & the 15-15 rule, carbohydrate counting.
  • Centers for Disease Control and Prevention (CDC)cdc.gov/diabetes — monitoring blood sugar, types of insulin, low blood sugar, diabetic ketoacidosis, managing sick days.
  • NIDDK / National Institutes of Health (NIH)niddk.nih.gov — insulin, medicines & other diabetes treatments; the A1C test; diabetes tests & diagnosis.
  • Mayo Clinicmayoclinic.org — hyperglycemia, diabetes management, diabetes & exercise.
  • Cleveland Clinicmy.clevelandclinic.org — injectable insulin chart, insulin pumps, injection technique.
  • U.S. Food & Drug Administration (FDA)fda.gov — insulin storage, biosimilar/interchangeable designations, product labeling (e.g. inhaled insulin).
  • GoodRxgoodrx.com — insulin cost, the $35 cap, patient-assistance programs, biosimilars and savings tools.
  • Healthline / Verywell Healthhealthline.com, verywellhealth.com — consumer explainers on insulin types and delivery.

This site is independent and is not affiliated with, endorsed by, or sponsored by any of the organizations listed. Organization names are used only to credit the sources of general information.

The important disclaimer, in plain words

This page is educational information only — it is not medical advice, diagnosis, treatment, or a dosing instruction. It does not tell you whether to use insulin, which product to use, or how much to take. Those decisions must be made with a licensed clinician, using a valid prescription filled at a licensed pharmacy. Never start, stop, or change insulin based on a web page. If you think you're having a severe low (cannot swallow, unconscious, seizing) or diabetic ketoacidosis (DKA), treat it as an emergency and call your local emergency number right away.