Thursday, December 5, 2013

Selecting the Best Insulin for Diabetic Cats when Cost Becomes Factor

I have an overweight (16 lb; 7.3 kg) male DSH cat who has been fairly well regulated on 3 units of glargine (Lantus) administered twice daily. He has been diabetic for over a year and has done well on a low-carbohydrate diet (less than 10% of calories as carbs).

However, the owner reports that the cost of glargine has risen again (now to just over $200 at our local pharmacy), so the owner wants to switch to another insulin preparation. Glargine has always been my first choice of insulin in diabetic cats so I'm not sure of which insulin would be the best (and cheapest) for this owner to switch to.

Any advice would be greatly appreciated. I'd still like to get this cat to go into remission, but I'm afraid that this will never happen if I stop the Lantus and change to another insulin preparation.

My Response:

The rising cost of all of the human insulin analogs, such as glargine and detemir, are indeed becoming a problem for many owners. If you and the owner decide to switch to another insulin preparation, you have 4 insulin preparations that could be considered (all should be given twice a day):
  1. Levemir (insulin detemir), another long-acting human insulin analog
  2. ProZinc (Protamine Zinc Insulin; PZI), a long-acting veterinary insulin preparation
  3. Humulin N or Novolin N (NPH insulin), an intermediate-acting human insulin preparation
  4. Vetsulin (porcine insulin zinc suspension; lente), an intermediate-acting veterinary insulin preparation
Cost comparison
Levemir (detemir): As far as cost, the retail price of Levemir will be about the same or even more than glargine (~$200 per vial), so that's not a good option for this owner.

ProZinc (PZI): A 10-mL vial of ProZinc insulin will be a bit cheaper than either a 10-mL vial of glargine or detemir. Most veterinarians will charge ~$125 - $150 for a vial of ProZinc, whereas both glargine and detemir will be ~$200 or more. That said, ProZinc is certainly not an inexpensive insulin preparation, especially when one considers that ProZinc is a U-40 insulin and each vial contains only 400 units of insulin. Since both glargine and detemir are U-100 insulins, a vial of these insulin preparations will contain 1,000 units of insulin. Therefore, the cost of ProZinc, at least per unit of insulin, turns out to be even more than the human insulin analogs.

Humulin/Novolin-N (NPH): The retail prices of an individual vial of NPH insulin (U-100) will vary widely depending on the pharmacy and its location. At the moment, the least expensive NPH product is Walmart's ReliOn brand (a Novolin insulin), which is sold at ~$25 per vial. However, most other pharmacies charge a retail price of $60 to $100 per vial.  So if you consider the cost per ml of insulin, NPH insulin would be the cheapest.  However, NPH insulin is also the least effective insulin in cats because of its very short duration, so I would not recommend this insulin in any cat, especially if excellent glycemic control or remission is the goal.

Vetsulin (porcine insulin zinc suspension): Vetsulin is available as a 10-mL vial of insulin in a U-40 insulin concentration. For veterinarians, the wholesale cost of the Vetsulin product is inexpensive (~$25 per vial). In most veterinary practices, the retail price of a vial of Vetsulin sold to pet owners will be approximately $50.

Therefore, the cost of a bottle of Vetsulin is similar or even less than the price of NPH insulin and costs much less (about 25-30%) than that of insulin glargine or detemir. But again, the total amount of insulin in a vial of NPH, glargine, and detemir (all U-100 insulins) is 1000 units, where a vial of Vetsulin (a U-40 insulin) contains 400 units, only 40% as much. So in the end, the client cost per unit of Vetsulin would be similar or slightly more than NPH but much less than Lantus, Levemir, or ProZinc.

Effectiveness of insulin preparations in cats
One must remember that it doesn't matter how much money we are saving if the insulin isn't working to control hyperglycemia and prevent ketoacidosis.

Most veterinarians would rank insulin glargine as the first choice of insulin in cats, then insulin detemir or PZI (not the compounded product (1), but FDA-approved ProZinc), then Vetsulin, then finally human NPH insulin as a very last choice (2-10). In my experience, all of the long-acting insulin preparations will show a similar effectiveness and remission rates (~35-50%), although individual cats may respond much better to one of these insulin products.

A number of studies have proven that Vetsulin will certainly control hyperglycemia in cats, especially if combined with a low carbohydrate diet (9,10). The remission rates for Vetsulin, on average, will not be as high as the long-acting insulins, but remission can certainly occur in cats on this insulin.

In this cat, however, remission of the diabetic state is highly unlikely. Most cats will go into remission within 3 months of starting insulin therapy (11-14). If the diabetic state has persisted for longer than 6 months, remission is highly unlikely. This is especially true in diabetic cats like your patient, in which an underlying cause of insulin resistance (i.e., obesity) is present.

Bottom Line

In this cat, given that remission has not occurred after 1-year of therapy with glargine and a low-carbohydrate diet, I would go with the least expensive insulin that will likely be effective in maintaining glycemic control and preventing ketoacidosis.  Overall, the best insulin fitting those criteria would be Vetsulin, which is relatively inexpensive and certainly would be more than adequate in most diabetic cats.

  1. Scott-Moncrieff JC, Moore GE, Coe J, et al. Characteristics of commercially manufactured and compounded protamine zinc insulin. J Am Vet Med Assoc 2012;240:600-605.
  2. Rand JS. Feline diabetes mellitus In: Mooney CT, Peterson ME, eds. BSAVA Manual of Canine and Feline Endocrinology. Fourth ed. Quedgeley, Gloucester: British Small Animal Veterinary Association, 2012;133-147.
  3. Marshall RD, Rand JS, Morton JM. Glargine and protamine zinc insulin have a longer duration of action and result in lower mean daily glucose concentrations than lente insulin in healthy cats. J Vet Pharmacol Ther 2008;31:205-212.
  4. Marshall RD, Rand JS, Morton JM. Treatment of newly diagnosed diabetic cats with glargine insulin improves glycaemic control and results in higher probability of remission than protamine zinc and lente insulins. J Feline Med Surg 2009;11:683-691. 
  5. Roomp K, Rand J. Intensive blood glucose control is safe and effective in diabetic cats using home monitoring and treatment with glargine. J Feline Med Surg 2009;11:668-682.
  6. Roomp K, Rand J. Evaluation of detemir in diabetic cats managed with a protocol for intensive blood glucose control. J Feline Med Surg 2012;14:566-572.
  7. Norsworthy G, Lynn R, Cole C. Preliminary study of protamine zinc recombinant insulin for the treatment of diabetes mellitus in cats. Vet Ther 2009;10:24-28. 
  8. Nelson RW, Henley K, Cole C. Field safety and efficacy of protamine zinc recombinant human insulin for treatment of diabetes mellitus in cats. J Vet Intern Med 2009;23:787-793. 
  9. Martin GJ, Rand JS. Control of diabetes mellitus in cats with porcine insulin zinc suspension. Vet Rec 2007;161:88-94.
  10. Michiels L, Reusch CE, Boari A, et al. Treatment of 46 cats with porcine lente insulin—a prospective, multicentre study. J Feline Med Surg 2008;10:439-451.
  11. Zini E, Hafner M, Osto M, et al. Predictors of clinical remission in cats with diabetes mellitus. J Vet Intern Med 2010;24:1314-1321. 
  12. Reusch CE, Hafner M, Tschuor F, et al. Diabetes remission in cats: a review. Schweiz Arch Tierheilkd 2011;153:495-500.
  13. Callegari C, Mercuriali E, Hafner M, et al. Survival time and prognostic factors in cats with newly diagnosed diabetes mellitus: 114 cases (2000-2009). J Am Vet Med Assoc 2013;243:91-95. 
  14. Gottlieb S, Rand JS. Remission in cats: including predictors and risk factors. Vet Clin North Am Small Anim Pract 2013;43:245-249.


Anonymous said...

Some compounding pharmacies will split a 10ml vial into five 2ml vials. This way, the 10ml lasts about 5 months, which significantly reduces the amount of waste and monthly cost.

That $200 for Lantus would then be stretched over 5 months, making it $40 a month.

Not all compounding pharmacies will do this, so it may take some calling. Each small vial is properly sealed, so it stays "fresh" and uncontaminated. We have encountered no difference in the fifth vial compared to the first.

Dr. Mark E. Peterson said...

Most veterinarians recommend using a vial of glargine for at least 3 months, even up to 6 months if kept refrigerated. If that's the case, the only advantage to splitting it into 5 separate vials would be to maintain greater sterility (less needles would be injected into each insulin vial), but this has not been a problem, at least not in my patients.

I certainly don't have a problem with your approach but no compounding pharmacy is going to do this for free, so splitting the 10-ml vial will likely add to the total cost.

CJ said...

Interesting article. My cat was on Lantus for 31 months before achieving remission 6 months ago. It looks like his remission is over, and I've been astounded at how the price of Lantus has increased.

I personally have found that, even with careful handling, I'm lucky if I get a vial of Lantus to last 3 months... generally two at the most. My cat's dose ranges anywhere from a few drops to 1u BID, meaning I would be wasting a good deal of the vial.

Instead, I use the solostar pens, and have found a pharmacy that will let me purchase pens one at a time rather than in a box of 5. While the upfront cost is higher, I'm able to use almost all the insulin, with a pen lasting 2-3 months.

Each pen has a rubber tip at the end. Instead of using the pen needles, I use a U-100 insulin syringe to draw the insulin out of the pen.

It's amazing that the cost per pen has risen from $41/each ($205 for a box of 5) to $63/each ($315 for the box) in the past three years. I was contemplating switching over to Prozinc, but seeing your breakdown in cost per dose has me staying with what worked for us before.

Dr. Mark E. Peterson said...

Thank you so much for your post. It's very interesting how a few cats can still go into remission, at least for a short time, after many months.

I am planning to do a post on the use on insulin pen vials, just as you describe. It's the most cost effective way to give insulin to cats (other than Vetsulin, which just doesn't always work as well).

You are lucky that you pharmacy allows you to buy a single pen rather than the box of 5. That's key to spreading the price over a few months instead of paying all the cost upfront.

Missy said...

Lantus also offers a savings card which says that you will pay no more than $25 on up to three SoloStar prescriptions. I had to purchase a box of five pens, but the Walmart Pharmacy refunded $100 when I brought the savings card in the next day (with my receipt, of course).

Dr. Mark E. Peterson said...

Thanks for the information - I wasn't aware of that offer!

Anonymous said...

Hi Dr. Peterson,

Thanks for this post!

My cat (turning 15 this month) was diagnosed with diabetes 4 days ago. He also has the very beginning of renal failure. He had gained a lot of weight this summer, then lost it but isn't skinny. He had symptoms for about a month and half (mostly just drinking a little more water). When I noticed changes in his hair (matted a little, some loss), I immediately brought him into a vet and got the diagnosis. I changed his diet from dry to wet and have already noticed a change (in the 4 days he's been on a low carb, low phosphorus high quality wet diet, his hair is starting to grow back, he can jump higher and he's more alert). The vet is planning on starting insulin Tuesday.

Question if cost isn't a factor:

The vet uses ProZinc but is open to using Lantus. For a newly diagnosed cat, would you say Lantus is a better bet?

Dr. Mark E. Peterson said...

Just depends on the individual cat. Both are good insulins. If one doesn't work well, then we change to the other.

Jessica Claerhout said...

Thank you so much for providing this article. I just recently discovered (last month) my cat (just shy of 13 yrs.), whom I've had my entire adult life, has diabetes. He went from 22 lbs. to 11.8 lbs. in one year. His fur had lost luster and he felt bony. His appetite and thirst were voracious, and the litter box had become constantly gross. He constantly whined. We lost his mother (she was 14) last year, so I was thinking perhaps it was just a similar end of life decline. I did not have the funds until recently to help either of them. Last month, his face swelled horribly with a tooth abscess, so I took him in and he was treated and it was also discovered he was diabetic. I had no clue that diabetes could have been the culprit for his decline! (In retrospect, I'm betting that his mother suffered the same ailment). My vet prescribed ProZinc and within the first dose, there was incredible and noticeable improvement. Within less than 2 weeks his blood sugar went from 560 to 160! We are dosing him 6 ml, twice a day. He is remarkably more content, his voracious appetite has diminished and he looks and feels (to-the-touch) better (more filled out physique, softer fur). In short, he is a different cat than he was a less than a month ago.

I never imagined I would have a diabetic cat and that I would administer insulin - but, his turnaround has been so remarkable, it seems apparent that with the insulin he has quite a bit more life ahead of him, so it seems the right thing to do. He is such a wonderful, big, orange, sweet kitty! However, I am worried about the cost. The ProZinc is $125 a bottle through my vet. I have not finished my first bottle, but it already appears to be half gone. I'm trying to mitigate the ethical/logistical/economical factors into how I will continue the treatment. If I can stretch it into 3 months, then it seems doable. I just started looking for a cheaper provider of ProZinc or other cat insulin this morning and saw Vetsulin. It appears to be about the third of the cost, so I wondered about the efficacy. Ideally, if my cat could recover, that would be perfect, but he is an older cat, so I'm prepared of the prospect that he may be on insulin for the rest of his life. If that is the case, the cost of Vetsulin is much easier to handle. I have not spoke with my vet about this yet - I suspect he would want to stick with the ProZinc, but maybe not. What are your thoughts about switching to Vetsulin? Maybe I should stick with ProZinc for the first few months and then possibly try switching? What can I expect long-term living with an insulin-dependent cat? His labs were all perfect except for his off-the-charts glucose level. Anything you can share would be greatly appreciated.


Dr. Mark E. Peterson said...

ProZinc is more likely to result in remission of diabetes, since it's a longer acting insulin. That said, if remission doesn't occur by 6 months, then it's highly unlikely to ever occur. So after 6 months, then I'd use the cheapest insulin you can find, as long as it controls the clinical signs of diabetes.