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Blood sugar guidelinesEdit

Absolute numbers vary between pets, and with meter calibrations. The numbers below are as shown on a typical home glucometer while hometesting blood glucose, not necessarily the more accurate numbers a vet would see (though many vets use meters similar to those used in hometesting). For general guidelines only, the levels to watch are approximately:

mmol/L mg/dL(US)
Blood Glucose Guidelines
<2.77 <50 Readings at or below this level are considered hypoglycemic when giving insulin,
even if you see no symptoms of it [1]. Treat immediately [2]
3.44-6 62-108 Non-diabetic glucose values for dogs who don't have diabetes [3].
5 90 Commonly cited minimum safe value for the lowest target blood sugar of the day when insulin-controlled.
5.5-10
100-180
Commonly used target range for diabetics for as much of the time as possible. [4]
10 180 "Renal threshold" for dogs and humans:
when excess glucose in the blood spills into the urine due to the kidneys not being
able to reabsorb it all and roughly when diabetic symptoms appear. [5][6]
See Hyperglycemia for long-term effects of high blood glucose.
14 250 Approximate maximum safe value for the highest blood sugar of the day.
Dogs can form cataracts at this level. Check for ketones. [7]
Increasing blood glucose levels indicate a lack of enough insulin;
this is how the body can switch from using glucose to using ketones for fuel. [8]
16.7 300
Check for ketones. High blood glucose values are an indication of insufficient insulin;
these conditions can make the body switch to using ketones for energy instead of glucose.
>20 >360 Check for ketones frequently; as blood glucose levels climb, the larger the insulin deficit.
The dog can feel any of numerous ill effects both short and long-term, see hyperglycemia for details.

What's too high? Edit

At high readings, combined with inadequate administration of insulin, and not eating or drinking enough, or an infection, animals can sometimes quickly develop diabetic ketoacidosis (DKA), which is immediately life-threatening. Always check urine for ketones at high readings. Of course, cats at much lower levels who have inadequate insulin supply coupled with infection, dehydration, or fasting can also develop ketones.

Some vets use a "sliding scale" regarding maximum permissible blood glucose values in dogs, "allowing" blind dogs or dogs with cataracts to use the concept of remaining under 250 mg/dL (13.88 mmol/L) at all times, with sighted dogs and dogs without cataracts ideally under 200 mg/dL (11.11 mmol/L).

Others apply the "under 200" (11.11 mmol/L) [9] for dogs at all times without exceptions.

Evidence from humans, mice, and in-vitro tissue studies show that damage to the pancreatic beta cells (the ones that make insulin) continues down to levels as low as 140mg/dL (7.77 mmol/L). [10]. This is why the AACE guidelines recommend average blood sugars (for humans) of no more than 170 mg/dL (9.44 mmol/L), preferably between 65 mg/dL (3.61 mmol/L) and 136 mg/dL (7.55 mmol/L). [11]

See hyperglycemia.

Factors Which Can Affect ReadingsEdit

  • Hemocrit The amount of red blood cells in the blood. Someone with higher hemocrit values will test lower than someone with normal hemocrit levels. Anyone with anemia or an anemia-related disorder will test higher than someone with normal hemocrit values [12]. If you know there is a possibility for either higher or lower than normal hemocrit values due to concurrent disease, discuss their possible impact on blood glucose readings with your health care provider.
  • Dehydration--Severe dehydration can cause inaccurate false low results [12].
  • Fats/Lipids--Excess cholesterol or triglycerides can also produce false meter readings.
  • Other Substances can affect your test results. They include uric acid (A natural substance in the body which can be more concentrated in those with diabetes.), glutathione (an anti-oxidant known also as "GSH"), and ascorbic acid (Vitamin C). Read the information for your meter to determine what substances, if any, may affect its accuracy--discuss these concerns with your doctor.
  • Altitude, Temperature [13][14], Humidity are all capable of having unpredictable effects on blood glucose readings. Both the meter and test strip inserts have more information about these issues. Store meter(s) and test strips according to their respective instructions.
  • Generic Test Strips are less-expensive copies of the branded ones. If and when manufacturers change anything about their meter(s) and/or branded test strips, generic manufacturers are not always advised of these changes. The type, amount(s) or concentration of the chemicals (called reagents) used in the testing process can change. Glucometers are sensitive to these changes and as a result, blood glucose readings may be inaccurate with the generic strips [15].

Why you still need Ketostix/KetodiastixEdit

While home testing blood with a meter can tell you what your pet's blood glucose levels are, most can't do blood ketone testing.

When you have high blood glucose levels, doing ketone testing with Ketodiastix or Ketostix is good practice to make sure your pet doesn't have ketones.

In a diabetic, any urinary ketones above trace, or any increase in urinary ketone level, or trace urinary ketones plus some of the symptoms of ketoacidosis, are cause to call an emergency vet immediately, at any hour of the day.

Good BG Readings but Positive Ketone ResultsEdit

When the bg readings are high enough to produce some ketones, you've taken action to bring them down and they are normal once more, it is possible to still see some positive urine ketone test results. Ketones show up in the urine right away. When you're getting normal bg readings, it means that there are no more ketones being produced. What you are seeing when you test urine for ketones and the blood glucose is in normal ranges are the "leftovers" of the ketones which were produced by the high bg episode. They will continue to show up in the urine for a while but their concentration will become less and less until they're gone [17][18].

Renal thresholdEdit

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Renal threshold-the point where glucose spills into the urine.

The renal threshold for glucose is defined as the blood glucose level where the kidneys begin excreting excess glucose into the urine. Certain side effects on the urinary tract begin at this level, and it's also fairly close to the level where other organ damage seems to occur, though there's no actual causal relationship. This number is a bit different for every animal [19].

Polyuria in diabetes shows that the body is unable to metabolize carbohydrates properly. Carbohydrates are turned into glucose, which is sent into the blood to feed the cells. The cells, lacking insulin, can't accept the glucose, so it remains in the blood causing hyperglycemia. The extra glucose in the blood accumulates there until the kidneys see it as an impurity to be filtered out and discarded. This point is known as the renal threshold.

When the renal threshold is exceeded, and the excess glucose begins to spill into the urinary tract, the glucose makes the urine attract water in what's known as the osmotic effect. This extra water in the urine causes the excessive urination, dehydrating the body, which in turn causes the excessive drinking of polydipsia.

  • The canine renal threshold for glucose is 180 mg/dL (10 mmol/L) [20][21][5][22]

While dogs and humans share the same renal threshold value of 180 mg/dl (10 mmol/L), the renal threshold of cats is 288 mg/dl (16 mmol/L); in cattle it's 108 mg/dl (6 mmol/L) [23].

What's normal? Edit

Normal blood glucose values for non-diabetic cats and dogs [24] range from 80-150 as measured on a vet's glucometer. Home glucometers used on animals tend to read a bit lower in the below-80 ranges because of the difference in size of red blood cells (erythrocytes) between species [25] and so will frequently show lower numbers (see chart above) that are not cause for alarm.

Diabetes being the "individual" disease it is, allows for many personal exceptions. A dog on the canine diabetes message board [26] who was tightly controlled developed hypoglycemia symptoms every time his blood sugar dropped to 85 or below. The solution was to slightly reduce his insulin which kept him at slightly higher bg levels.

InterpretationEdit

Somogyi

Somogyi rebound-a theoretical graph of what happens if you ignore the low bg numbers and focus only on the high ones created by the lows. As the insulin dose increases, the lows become lower, causing the counter-regulatory hormones to send the bg's higher in response. The only way to stop the extreme highs is to stop the lows; this means LESS insulin rather than more because it is the lows which are responsible for creating the highs [27].

Note that no single blood glucose reading is adequate to establish insulin dosage or recommended treatment. Blood glucose levels should be checked before each shot, but that alone is also not enough to determine if treatment is working. Please see curve and regulation and duration for more information on this tricky subject.

A single blood glucose reading is like a snapshot or a movie frame; it's a picture of how things were at that particular moment in time. While a movie frame can give us some information about its subject, it's when we put frame after frame together that we're able to see even more. If you see a cartoon of Mickey Mouse, you immediately recognize him, but Mickey really comes to "life" in animation. You see how he walks and talks, what he does and who his friends are. It's very much the same with blood glucose readings--the more of them you have, the easier it is to see where you're doing well and where you need to improve [28].

Both people with diabetes and pets with diabetes fall into trouble when anyone starts "chasing the numbers", or as Dr. Mike Richards puts it, "chasing the glucose level". [29] Changing insulin doses too frequently in search of the "perfect" blood glucose readings often winds up as hypoglycemia or Somogyi rebound, where the only way to correct the problem is LESS insulin rather than more. I16

ReferencesEdit

  1. Schermerhorn, Thomas (2001). Management of Insulin Overdose-pages 1-2. Compendium Standards of Care.
  2. Definition of Hypoglycemic values. Pierce County Animal Emergency Clinic/Animal Hospital of Pierce County.
  3. Serum Biochemical References Ranges. Merck Veterinary Manual.
  4. Diabetes for Dummies-Why is it Critical to Keep Glucose at 80-200. Valley Animal Hospital.
  5. 5.0 5.1 Canine Renal Threshold. Merck Veterinary Manual.
  6. Pathogenesis. Intervet.
  7. Chase, Peter. Understanding Diabetes-Chapter 5, Ketone Testing-page 30. Barbara Davis Center for Diabetes.
  8. Hanas, Ragnar (1999). Ketones Increase With Lack of Insulin-page 11-Insulin Dependent Diabetes in Children, Adolescents and Adults. ChildrenWithDiabetes.
  9. Diabetes for Dummies-Why is it Critical to Keep Glucose at 80-200. Valley Animal Hospital.
  10. Research connecting organ damage with Blood Sugar level. Phlaunt.
  11. Conversion from HbA1c to Blood Glucose level. Diabetic Gourmet.
  12. 12.0 12.1 Glucometer Information-Dehydration & Inaccurate Blood Glucose Results. US Food and Drug Administration (FDA).
  13. Test Strip Temperature Ranges. Childrenwithdiabetes.com.
  14. Blood Glucose Meter Reference-Listing of Meter Operating Range Temperatures. Diabeteshealth (2005).
  15. Glucometer Information- Possible Causes Of Inaccurate Blood Glucose Readings. US Food and Drug Administration (FDA).
  16. Blood Sugar and Stress. University of California.
  17. Hanas, Ragnar. Insulin Dependent Diabetes in Children, Adolescents and Adults-Page 11--Important-Ketones. ChildrenWithDiabetes.
  18. Hanas, Ragnar. Urine Ketones Decrease Slowly. Children With Diabetes.
  19. Taylor, Judith A. (2006). Harvesting the Gold-Urinalysis. District of Columbia Academy of Veterinary Medicine.
  20. Lab values. Animal Emergency center of Milwaukee, WI..
  21. Vetsulin (page 5). Intervet.
  22. Vetsulin Reference manual-Page 15-180mg/dl. Intervet.
  23. Taylor, Judith A. (2006). Harvesting the Gold-Urinalysis. District of Columbia Academy of Veterinary Medicine.
  24. Canine Diabetes Mellitus. New Hope Animal Hospital.
  25. Schall, William (2009). Diabetes Mellitus. DVM 360.
  26. Canine Diabetes Message Board
  27. Somogyi Rebound. wikipedia.
  28. Blood Glucose Averages. BD Diabetes.
  29. Richards, Mike. Regulating Insulin. Vet Info 4 Dogs.

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