Getting an insulin pump isn’t like buying a new phone. You don’t just unbox it, turn it on, and expect it to work perfectly. If you’re using continuous subcutaneous insulin infusion (CSII), your life now depends on understanding how the pump works - and how it can fail. This isn’t theory. It’s real. One missed alarm, one clogged cannula, one wrong setting, and your blood sugar can crash or spike dangerously fast. In Adelaide, where winters are mild but diabetes management never takes a break, I’ve seen too many people struggle because they were never taught the real rules - not the brochures, not the sales pitches, but what actually keeps you safe.
What’s Inside Your Pump? Basal Rates Are the Foundation
Your pump doesn’t just give you insulin when you eat. Most of the insulin you need - up to 50% - comes through a slow, steady drip called a basal rate. This isn’t one setting for the whole day. It changes. Every hour. Some people need more insulin at 3 a.m. because of the dawn phenomenon. Others need less after a workout. Most pumps let you set up to eight different basal profiles. You might have one for weekdays, one for weekends, one for illness, and one for exercise. If your basal rate is off, your blood sugar will drift all day long - even if you never eat a cookie.
How do you know if yours is right? Test it. Fast for 24 hours. No food. No boluses. Just your pump running on basal. Check your blood sugar every two hours. If it drops more than 1 mmol/L, your basal is too high. If it rises more than 1 mmol/L, it’s too low. Do this on three different days. That’s how you find your true basal. Most people guess. That’s why so many end up with high A1c.
Mealtime Dosing: Carbs, Correction, and the Hidden Trap
You think bolusing is simple: count carbs, press a button. But it’s not. Your insulin-to-carbohydrate ratio (ICR) tells you how much insulin you need for each gram of carbs. For most adults, that’s 1 unit per 10-15 grams. But if you eat a pizza, that number doesn’t work. Fat slows digestion. Protein can raise blood sugar hours later. That’s why extended or dual-wave boluses exist. A dual-wave delivers half the insulin right away, the other half over two hours. Use it for pasta, pizza, or creamy curries. Don’t just bolus and walk away.
Your insulin sensitivity factor (ISF) - or correction factor - tells you how much one unit of insulin lowers your blood sugar. Most people start with 1 unit = 3 mmol/L. But that’s just a guess. If your ISF is wrong, you’ll overcorrect and crash, or undercorrect and stay high. To test it: when your blood sugar is above 8 mmol/L and you haven’t eaten in four hours, give one unit of insulin. Check again in two hours. Did it drop 3 mmol/L? Then your ISF is right. If it dropped 5 mmol/L, you’re too sensitive. If it only dropped 1 mmol/L, you’re resistant. Adjust it. Do this every few months.
Infusion Sets: Change Them Before They Fail
Most people wait until their site hurts to change their infusion set. Bad idea. Cannulas clog. Skin gets irritated. Insulin doesn’t absorb right. The ABCD Clinical Guidelines say change your set every 2-3 days. No exceptions. Even if it looks fine. A 2022 study in Diabetes Technology & Therapeutics found that 32% of new pump users had infections or inflammation within three months because they left sets in too long. Rotate your sites: abdomen, thighs, upper arms. Don’t reuse the same spot every time. Lipohypertrophy - lumpy, scarred tissue from repeated injections - is real. It blocks insulin. You’ll think your pump isn’t working. It’s your skin.
Safety First: What Happens When the Pump Stops
Insulin pumps don’t turn off by themselves. If the tubing kinks, the battery dies, or the cannula pops out, the pump won’t alarm fast enough. You could be asleep. You could be driving. You could be at work. In two to four hours, your blood sugar will skyrocket. Diabetic ketoacidosis (DKA) can set in. That’s not a scare tactic. That’s what happened to 45% of users on Reddit’s r/diabetes who reported pump failures in 2023.
Always carry backup. Not just insulin. Not just syringes. Carry extra batteries, two infusion sets, alcohol wipes, and glucose tabs. Know how to give yourself a shot. If your pump fails, give yourself a long-acting insulin injection (like Lantus) to cover basal needs, and use rapid-acting insulin for meals. Don’t wait. Call your diabetes team. But don’t rely on them to save you.
When the Pump Can’t Help: Surgery, Pregnancy, and Illness
Need surgery? If it’s minor and you’ll eat within a few hours, your pump can stay on - if your glucose is between 4 and 12 mmol/L, your battery is full, and your reservoir isn’t empty. If it’s major? Turn it off. Switch to IV insulin. Hospitals know this. You should too.
Postpartum? Your insulin needs drop hard. Right after birth, cut your basal rate by 20-30%. If you’re breastfeeding, cut it another 10-20%. Your body is making milk, not babies. It doesn’t need as much insulin. Most new moms don’t adjust. They stay high. Then they blame the pump.
When you’re sick? Your body fights infection by making more glucose. Your insulin needs go up. Increase your basal rate by 20-50%. Check your ketones every 4 hours. Don’t wait for vomiting. If your ketones are moderate or high, go to the hospital. Don’t try to tough it out.
The New Generation: Closed Loops and What They Can’t Do
Devices like the Medtronic 670G and Tandem Mobi are called hybrid closed-loop systems. They adjust your basal rate automatically. That’s great. But they still need you to tell them when you eat. They can’t count carbs. They can’t fix a clogged cannula. They can’t replace your brain. A 2023 review in Nature Diabetes says these systems reduce hypoglycemia by 30% - but only if you use them correctly. If you forget to bolus, the pump won’t guess your meal. It’ll just keep giving basal. Your sugar will climb. You’ll think the tech saved you. It didn’t.
And don’t fall for the myth that these pumps are “artificial pancreases.” They’re not. They’re smart helpers. You’re still the pilot.
Training Isn’t Optional - It’s Survival
The American Association of Clinical Endocrinologists says you need at least 15 hours of structured training before you get a pump. Most people get two hours. That’s not enough. You need to learn how to test basal rates. How to use extended boluses. How to read your pump’s history. How to respond to alarms. How to change your set without tearing your skin. You need to practice. Do it at the start of the week. That way, your diabetes educator is available if you mess up.
After four weeks, you should have a follow-up. Your team downloads your pump data. They look at your glucose trends. Your bolus history. Your alarm logs. They see if you’re overcorrecting. If you’re skipping basal tests. If you’re ignoring low alerts. That’s how they catch problems before you end up in the hospital.
What No One Tells You
People talk about the convenience. The freedom. The better A1c. But they don’t talk about the stress. The constant checking. The fear of failure. The guilt when you forget to bolus. The shame when your site gets infected. The cost - $6,500 to $8,200 a year in the U.S., even more here with private insurance.
But here’s the truth: if you’re willing to learn, to test, to change, to carry backup, and to never stop asking questions - this pump can give you your life back. Not perfect control. Not magic. But real freedom. The freedom to eat when you’re hungry. To sleep through the night. To travel without fear.
It’s not about the machine. It’s about you.
How often should I change my insulin pump infusion set?
Change your infusion set every 2 to 3 days, no exceptions. Leaving it in longer increases the risk of infection, poor insulin absorption, and site reactions like lipohypertrophy. Even if the site looks fine, insulin delivery becomes unreliable after 72 hours.
What should I do if my insulin pump stops working?
If your pump fails, immediately switch to insulin injections. Use your long-acting insulin (like Lantus or Levemir) to cover your basal needs, and rapid-acting insulin (like Humalog or NovoLog) for meals. Never wait. Check your blood sugar every hour. Test for ketones if your glucose is above 13 mmol/L. Call your diabetes team, but don’t rely on them - you need to act now.
Can I use an insulin pump during pregnancy?
Yes, insulin pumps are safe and often preferred during pregnancy. Your insulin needs will rise sharply in the second and third trimesters. You’ll need frequent basal rate adjustments and tighter glucose targets (usually 3.5-5.5 mmol/L fasting). Postpartum, your needs drop by 20-30% immediately after birth, and another 10-20% if you’re breastfeeding. Always work with a diabetes specialist during pregnancy.
Why is my blood sugar high even though my pump is working?
High blood sugar with a working pump usually means insulin isn’t reaching your bloodstream. Check for a clogged cannula, kinked tubing, or a dislodged site. Test your infusion set by giving a small bolus and checking your glucose in 30 minutes - if it doesn’t drop, the set is likely blocked. Replace it immediately. Also review your insulin-to-carb ratio and correction factor - they may need adjusting.
Do I still need to check my blood sugar if I have a hybrid closed-loop pump?
Yes. Hybrid closed-loop pumps adjust basal insulin automatically, but they still require you to enter mealtime boluses. They can’t detect what you ate. You must still check your glucose at least four times daily - more if you’re sick, exercising, or changing settings. Relying only on the pump’s readings can lead to dangerous highs or lows.
What are the signs of diabetic ketoacidosis (DKA) with an insulin pump?
Signs include high blood sugar (above 13 mmol/L), nausea, vomiting, abdominal pain, fruity-smelling breath, confusion, or rapid breathing. If you have ketones in your blood or urine (above 1.5 mmol/L), treat it as an emergency. Give yourself a correction bolus, drink water, and go to the hospital. DKA can develop in under 4 hours if your pump fails or your infusion set is blocked.
What Comes Next
If you’re new to insulin pumps, start slow. Master basal rates. Learn how to test your insulin-to-carb ratio. Practice changing your set. Carry backup. Don’t rush into advanced features like temporary basals or dual-wave boluses until you’re confident with the basics.
If you’ve been on a pump for years and your A1c hasn’t improved, it’s not the pump’s fault. It’s your settings. Re-test your basal. Re-test your correction factor. Review your pump data with your diabetes educator. You might be missing the small things that make the biggest difference.
Insulin pumps don’t cure diabetes. But they can give you back control - if you’re willing to learn, stay curious, and never stop asking: ‘Is this right?’
Rod Wheatley
This is the most practical, no-BS guide to insulin pumps I’ve ever read. Seriously. I used to think my basal was fine until I did that 24-hour fast test-my sugar dropped 2.5 mmol/L. Changed my profile overnight. Also, the part about changing infusion sets every 72 hours? I ignored it for months. Got a nasty infection. Now I change them like clockwork. Don’t be me.