Blood Glucose Curves

The purpose of home blood glucose curves is to determine if your cat is on the optimum insulin dosage for its lifestyle.

Having convinced you that it’s a good idea to home blood test, and (hopefully!) having shown you how, it’s now time to do a full “Blood Glucose Curve”.

This is simply a series of blood tests taken over the course of a normal day to determine whether the insulin dose you’re giving is correct for your cat’s feeding and exercise habits.

Ideally, your first few blood glucose curves will be done over a full 24 hour period, so plan it for a weekend or holiday if you work away from home.

Take your first blood sugar reading in the morning, at injection time. Feed you cat, do your blood test and then inject your cat as normal, and allow your cat to wander/stay in/ go out/ just as they would on any normal day. The only thing that makes this day different from any other is that you’re taking blood sugar readings.

Make a note of the time of the first test and the amount of insulin given.

Take blood glucose readings every two hours after the first one. So if your first reading and injection were at 7:00am, the next will be 9:00am, then 11:00am, you get the idea!

You will hopefully notice that the blood sugar reading goes down to start with, then rises again as the insulin wears off.

If you are injecting twice a day, make a note of the time of the second injection and take a reading at this time too. Then, carry on taking readings every 2 hours until you have blood glucose numbers covering a full 24 hour period.

When you’ve recovered from your sleep deprivation (!) you will be left with a sheet of numbers. What you do with these numbers is then up to you. You could just take these numbers to your vet and discuss an adjustment to your cat’s insulin requirements if necessary.

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Personally, I find visual information easier to understand that numeric information, so I always plot the figures on a graph - there’s some I’ve done on the next page. The hours run across the bottom of the chart, and the blood glucose reading goes up the vertical axis. The yellow band represents the range I would like my cats blood sugar readings to be within – about 5 to 15 millimoles per litre (mmol/l). (The normal range for a non-diabetic cat is about 4 to 8 mmol/l.)

If you and your vet decide that an increase in insulin is required, take it slowly. Go up in small increments. The smallest change can make a huge difference to the readings you will subsequently get.

If you are increasing insulin, make sure it’s on a day when you’ll be home to watch your cat, and be on the lookout for signs of a hypo episode. After a few days at the new, increased insulin dose, do another full curve to see how this dose of insulin effects blood glucose levels.

If you are decreasing insulin, also go down in small increments and do another curve after a few days to see how this change has altered the blood glucose levels.

After some tweaking and curving, you will hopefully reach that longed for state of regulation.

It’s worthwhile doing a blood glucose curve (or at least a “mini-curve”) every couple of months, especially when seasons change. This is because if your cats are anything like mine, their habits and eating patterns change with the weather and a different insulin dose may be needed.

On the next page you’ll find a selection of curves I’ve done on my cats, and my interpretation of what the numbers are telling you.

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