Understanding Insulin Strengths

Common strengths of insulin used in dogs and cats are referred to as U-100 or U-40. “U” stands for unit. The numbers 40 or 100 refer to how much insulin (the number of units) is in a set volume of fluid – which, in this case, is one milliliter (1 ml) [referred to as units per ml]. For example, U-100 insulin has 100 units per milliliter and U-40 has 40 units per milliliter.

Understanding Insulin Syringes

To go with the different types of insulin, there are different syringes, including U-40 syringes and U-100 syringes. It is important to use the right syringe with the right insulin to achieve the correct dosage. Your veterinarian should prescribe syringes and insulin that match. The bottle and the syringes should each indicate if they are U-100 or U-40. Again, make sure they match.

It is possible to “convert” and mix and match the insulin syringes. It is generally not recommended because it can lead to deadly mistakes.

  • One unit of U-40 insulin is 0.025 ml in a regular syringe.
  • One unit of U-100 insulin is 0.01 ml in a regular syringe.

Using non-matching equipment is not ideal and should only be done after consulting with your veterinarian and confirming the “dose” and what equipment is being used (it is ideal to have someone double check you and your math – this is no place for experiments or errors).