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Guidelines to BG Interpretation

Due to the individual responses each pet has to insulin, differences in regulation levels being sought, and management style, it is important to review these guidelines with your vet and write down exactly what he/she wants you to do.

Blood Glucose Goals for Diabetics
 Non-Diabetic Normal BG
 Cats  Between 100 mg/dL  and 300 mg/dL  approximately 65-135 mg/dL
 Dogs without cataracts  Between 100 mg/dL  and 200 mg/dL  approximately 70-150 mg/dL
 Dogs already blind from cataracts  Between 100 mg/dL  and 250 mg/dL  approximately 70-150 mg/dL


Note that in discussions of Blood Glucose testing,

"peak" means peak insulin activity = lowest BG reading!

BG Action Plan

Getting a BG reading is just the first step, you need to plan what actions you will take in situations you might face from an hypoglycemic crisis to hyperglycemia. Review these guidelines with your veterinarian and discuss what actions you should take in various situations, especially how to decide when it is an emergency and your pet should be rushed to the vet. Pets have a knack for getting sick when vets are busy or unavailable: know what steps to take until you can reach veterinary help.

Emergency Contact Information
Know who covers when your vet's office is closed--it is often a regional Emergency Vet Hospital. You should have the name, office hours, phone number, and location of your vet and whomever covers for your vet written down by your phone and on a card in your wallet, including directions on how to get there. Emergency numbers and directions are especially important when someone else is caring for your cat, but they can save you precious time in a crisis, when it is hard to stay calm.

Be sure your vet has explained the symptoms of hypoglycemia (low blood sugar, BG at or below 50) and how serious it is.

Hypoglycemia Symptoms
Mild symptoms: hunger, aggressive behavior, irritability -- just like Bob when he's hungry!
Moderate symptoms: stumbling, wobbly legs, walking in circles, whining or meowing strangely--appears drunken. Administer 1-2 tablespoons of Karo syrup for a 10 lb. pet. Then what do I do?
Severe symptoms: seizure, blindness, or unconscious. What do I do?

Hypoglycemia Treatment

You should know how and be prepared to treat hypoglycemia with Karo syrup or another sugar source (pancake syrup usually 1-2 Tablespoon/10 lbs). Honey may be used, but has a risk of botulism and is not generally recommended for sick animals. Caution: some oral hypoglycemic medications interfere with the absorption of carbohydrates (Precose, acarbose). If your pet is receiving an oral hypoglycemic and becomes hypoglycemic (usually only occurs if insulin was also given), you will need pure glucose to raise BGs quickly (??Karo has fructose--will it still work??). You should monitor very closely because you will probably need to repeat the glucose at least once before any food given will be able to help raise BG levels.

If your pet is able to eat, Karo is followed by dry food (carbohydrates), and then protein. If your pet is conscious but unable to eat, Karo should be dribbled on the gums with a feeding syringe [go slowly to avoid choking]. Harry says canned whipped cream is much tastier than Karo, and makes kibble a gourmet treat.

If pet is unconscious, Karo can be rubbed on the gums with your finger and repeated as needed while rushing animal to your vet or an emergency vet hospital.

If you get a very low BG reading (50 or less) and your pet is showing symptoms of hypoglycemia, you should immediately treat for it. Not all pets show symptoms of hypoglycemia, even when their blood glucose is very low. If your pet is not showing symptoms, you should immediately repeat the test, and check the meter with Normal Control solution. If the low reading bears out, treat your pet for hypoglycemia, taking into consideration where you are in the food/insulin cycle i.e. if you haven't reached peak (the lowest BG point) yet, you give more Karo than you would if later in the cycle.

If NO Hypoglycemia Symptoms:
The BG is 50 and I think it may go lower, do I give food, or Karo? How much of each? Repeat how often?
The BG is 50, but I think it will go higher soon. What do I do?
The BG is under 50, what do I do?

Lower than Normal BG (or unusually low BG for that point in food/insulin cycle):

Factors to consider:

  1. Is the BG reading correct?
  2. Was there an adequate blood sample?
  3. Is the glucometer functioning correctly?


  1. Redo blood test. Is result the same?
  2. Check glucometer with Normal Control solution to ensure that it is working correctly.

If the BG result is approximately the same and the meter checks out ok with the Normal Control solution, consider where you are in the insulin cycle (pre-shot, peak etc.) and consider your action based on the projected estimate of how low your pet might drop at peak and whether you will be able to be there to continue monitoring and to intervene with food and/or Karo, if needed.

Lower than Normal BG at pre-shot:

Do not give any insulin if pet is already in the desired normal range of BG (~100-300 for diabetic cats, ~100-200 for diabetic dogs), unless your vet has specifically advised you what dosage to give at what BG number. DO NOT give insulin to a pet whose BG is below 100.


Prorate insulin based on the average drop that occurs normally per unit of insulin. Until you have collected a series of pre-shot and peak BG readings with this insulin, at the current dosage, you do not have enough information to estimate an average drop, be VERY cautious.

A cat with a usual pre-food/pre-shot BG of 300, routinely receives 3 units of Ultralente insulin, and peaks around 150, suggesting each unit of insulin drops him 50 points. A subsequent pre-food/pre-shot BG finds the cat at 200. Knowing the cat drops 50 points per unit you would know that a safe dosage would be about 1 unit to get him to his usual peak. Another unit would take him to around 100, which is at the lower BG limit of the 100-300 pt range, that most try to regulate pets within. Because cats don't necessarily respond in a linear mathematical manner, the safer dosage would be around 1 unit. Response is often non-linear, i.e. 1 unit when BG is low may cause more drop than when BG is high.

Lower than Normal BG Midway Between pre-shot and Peak:


This requires an estimate based on your current BG reading and how much lower it will likely drop before peak. If it's substantially lower and dropping toward the 100 BG mark, give a small meal preferably of dry food since that will be digested faster. Dry food is higher in carbohydrates which are absorbed faster than protein or fat. If BG is already nearing hypo levels give Karo and kibble. Then monitor hourly and provide additional food (including protein) and/or Karo as needed until peak has past and at least 2 BG readings have shown BG levels to be on the rise.

Whether to give another shot of insulin if your kitty is on 2 shots a day depends on how low he went, as well as the BG level at the next shot time. If it was hypo level, it's usually best to wait till the next day. If your kitty has a tendency to produce ketones, and the pre-shot BG is high enough, you can give a small conservative prorated dosage. You then reduce the insulin dosage or increase the food amount or can do a combo depending on the severity of the incident. You can also feed a little earlier before the shot to give the glucose a head start.

BG's Higher than Normal (higher than usual for your pet at this point in the food/insulin cycle):

There can be many causes of BG's higher than normal and the typical procedure is to hold off on dosage increases until you assess all possibilities using a process of elimination.

Factors to consider:

  1. Increased food intake or food eaten at inappropriate times is a major reason for regulatory problems and should be ruled out first.
  2. Stress, certain medications, and infections can cause higher BG's and they should also be evaluated as possible causes for the sudden BG elevation.
  3. Somogyi rebound also needs to be eliminated and should particularly be suspected if dosages were raised recently. Standard protocol is to reduce your insulin by approximately 25% for 72 hours to see if the BG's go down.
  4. A problem with insulin absorption can cause erratic, unusually high BG levels. Injection technique, temperature, and body location can affect the absorption pattern. The typical remedy is to alternate sites and check injection technique to see if problem resolves.
  5. Insulin potency may also be a factor--improper storage or age can affect its viability. The only solution for this is to open a new bottle to see if the BG's change.
  6. There are also inexplicable aberrant high BG's that defy logic but usually are temporary.

Once these factors have been eliminated and subsequent BG's have remained high, discuss increasing the insulin dosage with your vet. You would usually increase the dosage only .5-1 u at a time and allow several days for the pet to adjust to the new dosage, then do a curve to gauge the results.


Diabetes mellitus*
"Stress" (cat)*
Postprandial (after eating---soft moist foods)
Hyperadrenocorticism* (i.e. Cushings, often a tumor of pituitary gland or adrenal gland, more dogs than cats)
Acromegaly (cat, pituitary gland disorder)
Diestrus (a female in heat)
Pheochromocytoma (dog)
Pancreatitis (inflammation of pancreas)
Exocrine pancreatic neoplasia (tumor affecting pancreas)
Renal Insufficiency (kidney disease)
Drug therapy,* (i.e. glucocorticoids, progestagens, megestrol acetate)
Glucose-containing fluids
Laboratory error
*Common cause

Source: Ettinger's and Feldman's Textbook of Veterinary Internal Medicine


When your Pet Won't Eat--Anorexia:

There are times when a pet won't eat and the dilemma is whether to give or not give insulin. Consult your vet! Cats can develop fatty liver disease within 2 days, if they don't eat. This is an extremely serious problem and is often fatal.

All diabetics need some insulin in order to allow the use of glucose as the primary energy source. If there are glycogen reserves, the liver will provide glucose when not enough is obtained from food. However, those glycogen reserves may already be depleted after a hypoglycemic event. If not eating on their own, anorexic cats should be syringe-fed meat baby food (at least 2 small jars/day, diluted with water until it's a bit soupy) and given a prorated amount of insulin based on the pre-shot BG.

??Similar recommendation for dogs--syringe feeding??

When a diabetic pet is at a normal BG and anorexic the situation becomes more problematic. In general, if you can give a small amount of insulin with some syringe-fed baby food that will be enough to avoid both hypoglycemia and ketosis. If it's long acting insulin, you may only need one shot a day. This is a very delicate situation and any insulin given should be a very small amount to determine the reaction. A good starting point is about .5 units.

If a diabetic pet is at a low BG and anorexic the best advice is to monitor the situation with BG tests and ketone tests, hydrate, syringe feed and raise the BG level up so that it's possible to give a small amount of insulin.


Pets with high BG levels often lose their appetite and refuse to eat. Pets that are sick with diarrhea and/or vomiting become dehydrated and are also at risk. The body will breakdown fat for energy, producing ketones as a by-product, any time there isn't enough insulin to utilize available glucose or there isn't enough glucose (from food) for the available insulin to process.

While most often associated with high BG levels, (some meters prompt you to test for Ketones at readings 240 mg/dL or above), ketones can occur at normal or low BG levels. Use Ketodiastix or Ketostix to test urine for ketones. An acetone chemical smell on your pet's breath is a sign of diabetic Ketoacidosis (DKA) and is potentially life threatening. Notify your vet if your pet tests positive for ketones. If ketone level is high, get your pet in on an emergency basis. The vet will usually need to hospitalize for initial hydration (sub-cutaneous or IV fluids) and administer short acting (Regular) insulin to flush out the ketones. You may need to continue treatment by administering sub-Q (subcutaneous) fluids at home, for a time.

For all these situations: when do I call the vet, when do I immediately take my pet to the vet or emergency clinic?

Use Computer Software to Plot Your BG Data and See Trends

The Elite XL, Dex, FastTake, Precision QID and Accu-Chek Advantage have a data port which will allow you to download the readings in the meter memory to a computer, and use software to plot graphs of BG readings over time.  To use the automatic download, you will have to purchase the special cable and get the software designed to work with your particular meter. Bayer's WinGlucofacts can be downloaded free on their website, LifeScan's InTouch software must be purchased ~$69.  Medisense offers Precision Link and Roche's Accu-Chek Advantage uses a program called Cambit. New meter models will probably all include the data port feature. 

There are advantages to recording each reading as you go, along with notes about any changes in feeding schedule, appetite, or  insulin (everyone "misses" sometime).  You don't have to buy a cable and do a memory download to get all the fancy graphs, just get some software and type in each BG reading yourself. We find Bayer's WinGlucofacts Glucose Trend graph especially helpful--it graphs BG reading by date and time, for up to a month on a single page. You can spot patterns easily when BG data is plotted. We usually write-in the type of insulin and mark each dose given at the top of the graph, indicating the pre-shot BG reading.

Many people have Microsoft Excel and have set up a spreadsheet with date, time, BG reading and notes columns. You can select the range of times and BG readings for a day and create a bar chart of those readings. Although the times are labeled, a bar chart doesn't plot relative to the time.

Bayer Win Glucofacts Sample Data Screens