Out of curiosity if you don't mind, how many vials/[unit time] do you need, and is this variable per person or mostly just between people?
Additionally my pump (tandem x2) has a lot of loss due to their loading system. For 300 units loaded, you get 250 deliverable units. Reloads happen about every 5 days.
For use per month, I have 2 vials per month prescribed.
If you are thinking about cost: pump insertion sets and continuous glucose monitoring sensors are all very expensive as well.
I use Lantus as my long acting insulin, and Humalog as my fast acting insulin. I receive a shipment of three 10ml vials of each every 3 months (so I use 1 a month). I use 30 units of Lantus a day, and a variable number of units of Humalog, averaging 25 units a day. Thus, 1 vial of Lantus lasts me slightly over 30 days, which is how long you should use a vial of insulin before replacing it.
Figuring out how many units of insulin to take can be difficult. This year I got a Freestyle Libre 2 glucose monitor which has alarms which will alert me if my glucose goes above or below preset limits. Fortunately, I am sensitive to hypoglycemia; sensitive enough that I will wake up if I go low while I am sleeping, but I can still get as low as a glucose reading of 40 point before I feel the effects, which upsets me and freaks out my wife. The alarm is set for 80 points, so I can take some carbs before I get seriously hypoglycemic.
I adjust my Humalog injections based on my glucose readings and my carb intake using a formula I have adjusted over long experience. I may take as little as 1 unit (if I just need to bring my glucose reading down) or as much as 12 units with a meal, but most of the time I take about 8 units with a meal.
My wife requires quite a bit more insulin while pregnant for example - she had to make changes to her pump's settings while in the hospital to accomodate it.
What I found: 1 unit of insulin will cover 10g of carbohydrates [1]
Humalog insulin comes in 3 mL (300 units) vials or 10 mL (1000 units) vials. [2]
The list price of a Humalog U-100 10 mL (1,000 units) vial is $274.70 [3]
In type 1 diabetes, most people need a total of 0.5 - 0.8 units of insulin per kilogram of body weight each day. [4]
In patients with type 2 diabetes, marked obesity, and insulin resistance, total daily insulin doses of 200 to 300 units are often required. In this setting, management for most patients includes a total of 1.0 to 2.0 units of insulin per kilogram per day; thus, in very obese patients, a larger total dose is required. [5]
In type 2 diabetes, the average weight is 96.5kg - 98.9kg. [6]
The average American weight in 2020 was 181 lbs. So around 82kg. [7]
With the above details, in type 2, about 100 - 200 units are needed per day. That’s $989 - $1978 per year. In type 1, $494 - $791.
1. https://www.medicalhomeportal.org/link/3822
2. https://www.nationwidechildrens.org/family-resources-educati...
3. https://www.lillypricinginfo.com/humalog
4. http://www.diabeticretinopathy.org.uk/prevention/insulindose...
5. https://www.patientcareonline.com/view/insulin-dosing-how-hi...
6. https://care.diabetesjournals.org/content/29/3/493
7. https://news.gallup.com/poll/328241/americans-average-weight...
This varies significantly from patient to patient actually. The same goes for basal rates (how much insulin you need to maintain a healthy blood glucose level excluding what you eat). As you mentioned, weight is a big factor but so are other things like age, sex, diet, activity level, stress level, and just how well your body reacts to the insulin. Some people respond very well to artificial insulin while others just don't for some reason. I believe it can also depend on how long you've been using insulin. Your body can slowly stop responding as well as it used to.
The numbers you came up with as an average sound pretty reasonable, but it's important to remember that daily dosage will vary quite a bit between individuals.