Diabetes mellitus is the condition of hyperglycemia (high blood glucose) and glucosuria (glucose in the urine) caused by absence of the hormone insulin, or failure of the cells of the body to be able to respond to insulin.
Diabetes mellitus is the condition of hyperglycemia (high blood glucose) and glucosuria (glucose in the urine) caused by absence of the hormone insulin, or failure of the cells of the body to be able to respond to insulin. Diabetes mellitus in veterinary patients can most often be compared to human adult onset diabetes (type 2), and juvenile onset diabetes is rare in veterinary patients. Patients may present with few clinical signs, in relatively good health (uncomplicated diabetes mellitus), or may be weak and dehydrated with severe electrolyte abnormalities (ketoacidotic diabetes mellitus).
The most common clinical signs include weight loss, polyuria/polydipsia, increased or decreased appetite, unkempt hair coat, dandruff, sudden onset blindness (in dogs from cataract formation secondary to diabetes), and hind limb weakness (from diabetic neuropathy in cats) . In dogs and cats that have progressed to diabetic ketoacidosis, vomiting, anorexia, and lethargy are common complaints. Physical examination findings can reveal thin body condition, cataracts (dogs), dehydration, and mental dullness. Animals with recent onset diabetes mellitus can have a relatively normal examination.
Laboratory testing to diagnose diabetes mellitus is relatively straightforward, and diagnosis can be confirmed at the time of evaluation in some cases with in-house testing. Elevated blood glucose is the mainstay of diagnosis; however keep in mind that hyperglycemia may be from diabetes, or secondary to a stress response, especially in cat. Handheld glucometers that are used by human diabetics can be used in veterinary practice as well. The actual glucose reading obtained with these devices is often slightly lower than the actual blood glucose as measured with a biochemistry analyzer. If blood is being sent to an outside laboratory for analysis, remember that blood glucose measurement can become falsely lower if the serum is not separated from the clot in a timely manner. Finding glucosuria in the face of hyperglycemia can distinguish diabetes from stress response if clinical signs are consistent. In animals with diabetic ketoacidosis, many other biochemical abnormalities can occur including elevated blood urea nitrogen (BUN), creatinine, low or normal sodium, low potassium, phosphorous and magnesium.
Management of the Uncomplicated Diabetes Mellitus patient
Initial therapy can be done either in the hospital, or at home, depending upon clinical status of patient and time constraints of client and veterinary staff for diabetes training. Initial client training is the most crucial step to insure successful treatment both initially, and over time! Most clients have no prior knowledge of diabetes, or medical training, and therefore have anxiety about their ability to treat successfully without hurting their pet. Appropriate diabetic instruction for a newly diagnosed diabetic will take about 45 minutes, and should consist of discussing and demonstrating at-home monitoring techniques, schedules, and diet therapy, discussion of care and handling of insulin, and observing the client successfully measure and inject their own animal.
Client Protocol for Diabetic Management
Maintain a diabetic logbook
· Daily entries for urine test results if the client is doing urine testing, observation of clinical signs, and amount of insulin administered
· Pages should be attached to book (e.g. spiral notebook better than loose-leaf)
· Bring logbook in for appointment to review
· Goal of therapy is for insulin to be available for the body to use, and for glucose to be controlled by insulin, for a 24-hour period
· Human oral drugs to lower blood glucose do not work in dogs, and rarely work in cats
· Every animal responds differently to insulin, therefore dose and treatment plan must be customized for every pet over time
· Insulin regulation is a gradual process, and takes days to weeks at home
· Insulin is classified by duration of activity (short, intermediate, long), by source (beef, pork, human recombinant), and by strength (units per ml)
· For at-home management, an intermediate or long-lasting insulin are prescribed – the choice is dictated by the species, historical response, approved types of insulins, and clinician preference
· Starting dose approximately ½ unit/kg in the healthy diabetic
· Starting dose is a test dose, and will need to be raised or lowered based upon patient response. Best to start conservatively
· Insulin syringes are marked in 1-unit increments, and should match the insulin strength (e.g. U-100 insulin has 100 units/ml, and U-100 syringes have 100units/ml
· Clients should be instructed on the proper method to measure insulin into the syringe, and should be witnessed administering an injection to their own pet while being coached at the veterinary hospital
· If the client accidentally “misses”, or goes through the skin, and insulin is not administered to the patient, the client should not try to estimate the amount lost. That dose should be skipped, and administration should resume as normal for the next 12-24 hour period.
· Some clients benefit from further at-home instruction by a visiting technician
Diet therapy and feeding schedule
· Patient should show good interest in food, and eat every day
· Dogs: Divide total daily food intake into 2 meals given 12 hours apart. Consider increased fiber diet unless the patient is underweight
· Cats: Typically, diets that are higher in protein and lower in carbohydrates are recommended. May or may not be able to feed twice daily depending upon the cat – some cats are grazers. Dry or canned foods can be fed as long as there is daily food intake without vomiting
· If DM is well controlled, drinking and urinating should reduce, appetite should become more normal, and weight gain and coat improvement should be noticed
· The client should be instructed to call if any signs of hypo- or hyperglycemia are seen (see below)
· May test urine daily for glucose and ketones at home
· Call if ketones positive – indicates insufficient insulin, and may indicate onset of illness
· Glucose is usually slightly positive in diabetic pets managed with insulin
· Some animals require at-home or in-hospital blood glucose testing to evaluate duration and activity of insulin
· Single blood glucose measurements usually not helpful for regulation since glucose will change over time
· Glucose curve is done by measuring blood glucose every 2 hours for 12 hours (on BID protocol) to 24 hours (on SID protocol)
· Look for trend in blood glucose over time to determine when peak activity occurs, and how long insulin lasts
· Usually, client feeds in the morning, administers insulin, then presents pet for testing
· May be done with hospital personnel feeding and administering insulin
· Stress will elevate blood glucose results in hospital
Accurate patient records of dose adjustments and patient changes are crucial since adjustments may be made at home instead of in the hospital, and more than one person may be talking to the client
Signs of hypoglycemia (low blood sugar)
· If insulin overdose occurs or the pet's insulin needs change, hypoglycemia may result
· Symptoms include weakness, disorientation, stumbling, drooling, seizures, coma, or, rarely, death
· Client instructions should include a review of these signs
· The client should always have corn syrup available, and give 1-3 Tbsp orally if symptoms are seen. If symptoms resolve, then a meal should be fed, and no more insulin should be given until consulting with their veterinary hospital. If symptoms do not resolve within 10 minutes, then client should seek emergency medical attention
· Clients should be familiarized with the procedure for contacting the veterinarian on emergency
Signs of hyperglycemia (high blood sugar) or insufficient control
· Include PU/PD, failure to gain weight, unkempt hair coat, development of ketones in the urine, lethargy, depression, loss of appetite
· Although usually not an emergency, should seek medical attention promptly
· May indicate a change in the medical condition (infection, metabolic disease, other hormonal disease)
Long-term follow up
Initially, recheck visits should occur weekly for 2-3 weeks to monitor weight, clinical signs, and body condition, and review logbook. Telephone updates once or twice weekly are helpful initially to evaluate symptoms and any changes. Over time, 3 to 4 visits a year should be sufficient for most monitoring in the well-controlled diabetic patient. Patients with diabetes mellitus may be more prone to urinary tract infections, and should be monitored if any signs are seen. Occasionally, diabetes mellitus in cats may resolve without warning or reason. Usually, those cats present with insulin overdose
The Complicated Diabetic: Diabetic Ketoacidosis In-patient Management
Diabetic ketoacidosis (DKA) develops in animals that have an absolute need for insulin. In some cases, the animal has been previously diagnosed with DM or signs have been present for some time that are consistent with DM; whereas in other animals minimal signs of DM are present before the diagnosis of DKA is made. Although long-term management following stabilization follows the outpatient DM management described above, animals with DKA have critical fluid and electrolyte abnormalities that necessitate in-patient management and stabilization in a facility with 24-hour nursing care.
Goals of fluid therapy include volume resuscitation, rehydration, and correction of electrolyte abnormalities. Intravenous fluid therapy also lowers blood glucose by dilution, and increases glomerular filtration rate to increase glucose loss. Historically, recommended replacement fluid for treatment of DKA has been 0.9%NaCl. Isotonic replacement crystalloid solutions are indicated until dehydration has been corrected. Hypotonic fluids (0.45%NaCl) should be avoided initially because rapid shifts in osmolarity can precipitate cerebral edema and coma in the DKA patient. The fluid dose should be calculated to include maintenance needs, dehydration, and contemporary losses from vomiting or diarrhea. Following institution of fluid therapy, frequent evaluation of hydration status is imperative to avoid overhydration. Hydration may be estimated by physical examination, and more objectively measured by monitoring body weight two or more times a day. Fluid dose should be recalculated to meet individual needs.
Hypokalemia is the most common electrolyte abnormality associated with DKA.
Clinical signs of hypokalemia include muscle weakness, cervical ventroflexion in cats, cardiac arrhythmias, and respiratory muscle failure. Potassium may be supplemented by adding potassium chloride to intravenous fluids based upon a potassium replacement scale, or by calculation of potassium replacement. Guidelines recommend administration at a rate of not more than 0.5mEq/kg/hr. Patient potassium should be rechecked within 6-8 hours to adjust therapy as needed. In addition, withholding insulin and bicarbonate therapy, and avoiding rapid intravenous fluid administration until potassium therapy has been initiated may prevent worsening of hypokalemia.
Hypophosphatemia may be recognized at presentation, or following treatment of DKA. Initial dose of phosphorous is 0.03-0.12 mmol/kg/hr CRI in 0.9%NaCl for the first 6 hours, with reevaluation of serum phosphorous and adjustment of dose as needed. Alternatively, phosphorous may be supplemented by administering one-half of the potassium requirement as potassium phosphate (KPO4). Frequent serum phosphorous monitoring to avoid iatrogenic hyperphosphatemia and hypocalcemia is warranted. Packed cell volume should be monitored frequently since hypophosphatemia may result in acute onset hemolytic anemia.
Metabolic acidosis is common in DKA. Bicarbonate administration to correct metabolic acidosis in patients with DKA remains controversial since it can be harmful. If the patient is alert and mentally appropriate, bicarbonate therapy should be withheld. In patients with severe acidemia, with blood pH less than 7.10-7.15, and bicarbonate values less than 8mmol/l, and clinical signs of metabolic acidosis, bicarbonate therapy should be considered.
Insulin therapy reduces blood glucose and reverses ketogenesis. In addition, insulin therapy can contribute to life threatening complications such as hypoglycemia, hypokalemia, and sudden changes in osmolality. Careful planning of appropriate therapy tailored to the individual, and consistent patient monitoring can help to avoid serious complications. Only regular insulin should be used in the initial treatment of DKA. Regular insulin has a rapid onset of activity and short duration of action. In addition, regular insulin can be administered intravenously, intramuscularly, or subcutaneously. Once the patient is stabilized, insulin with a longer duration of activity is indicated for long-term maintenance.
Three insulin protocols for initial management of DKA have been described in the veterinary literature: intravenous constant rate infusion, hourly intramuscular (IM) insulin, and IM insulin administered every 4-6 hours. Each protocol has advantages and disadvantages; therefore, selection of protocol should be made based upon the experience and preference of the managing clinician. Similarities between the three protocols include the use of regular insulin to gradually lower blood glucose, administration of 2.5-5% dextrose in intravenous fluids when blood glucose falls below 250mg/dl, frequent assessment of individual patient response to therapy, and change to intermediate-acting insulin for long term outpatient management once ketogenesis has resolved and clinical condition has improved.
Prognosis can be variable, depending upon the condition of the animal at the time of presentation, and the care the owner can provide. Some animals are relatively stable and respond well to treatment over months to years, while others respond poorly to treatment and are difficult to manage. Diabetic care requires a long-term commitment on the part of the owner, both of time and money. For these reasons, some clients may elect euthanasia as an option instead of treatment.
Sample of Client Instructions Handout:
Client instructions for care of diabetes mellitus
Prepared for: _______________________________________
Your pet has been diagnosed with Diabetes Mellitus. This disease is caused by a lack of the hormone insulin that is normally made by the pancreas (a gland in the abdomen). The cells of the body cannot absorb glucose (sugar) without insulin. Glucose levels in the blood increase, glucose is lost in the urine, and the cells of the body starve. The end result of these changes is weight loss, increased drinking, increased production of urine with “sticky” urine, and increased appetite. Without treatment, diabetes mellitus eventually causes severe illness with loss of appetite, vomiting, depression, and dehydration. Diabetes mellitus is usually a permanent condition. Diabetes mellitus is treatable, but is not curable.
Diabetes is most commonly treated by the administration of injectable insulin at regular intervals, and altering diet and feeding schedules. Response to insulin is evaluated by observation of symptoms, and monitoring blood and/or urine tests over time. Please follow the instructions below to treat your pet.
1. Keep a logbook:
Maintain a daily record of your pet's appetite, urine test results (if monitoring), insulin administered (quantity and time), and observations (urinary habits, drinking, vomiting, lethargy, etc.). Present this logbook for evaluation during your regular appointments, to help with decisions in adjusting treatment.
2. At Home Urine or Blood testing:
(Modify this section as needed for the individual patient and practice)
3. Feeding schedule:
Your pet should be fed _____________________________ diet. The appropriate feeding schedule for your pet is _____________________________________________________
Food intake is important when treating diabetes mellitus, to insure a source of glucose to be taken up by the cells. If your pet stops eating, is vomiting, or food is being withheld prior to anesthesia, please administer half of the normal amount of insulin, and contact your veterinarian for further instructions.
4. Insulin administration:
Your pet is being treated with ___________________________ insulin, given by injection under the skin __________ times a day. Your starting dose is _________________. Your insulin syringes are __________________. Twice daily injections should be given at twelve-hour intervals. Schedule these for times that will be convenient for you. Do not give injections closer together than 10-hour intervals.
Insulin should generally be kept in the refrigerator. Do not freeze insulin. If you are traveling, you may keep insulin at a comfortable room temperature for you. If you accidentally leave insulin at room temperature for the day, it is still effective as long as it has not gotten excessively hot. Please replace your bottle of insulin at three-month intervals if you are using small doses, and there is insulin remaining at that time. Insulin syringes require a prescription, however insulin does not.
Evaluate your pet for attitude and appetite before each injection. If your pet seems normal and is eating, gently mix the insulin by rolling or inverting the bottle until the insulin is a uniform color. Shaking the insulin can inactivate it. Insert the insulin syringe and needle into the center of the stopper, invert the insulin bottle, and withdraw the prescribed dose of insulin. Small air bubbles will not affect the dose.
To administer the injection, adequately restrain your pet, lift a small amount of skin anywhere from the nape of the neck to the shoulder blades, insert the needle fully under the skin, and push the plunger of the syringe. Withdraw the needle, and dispose of the needle and syringe into a puncture proof container. There are no vital structures that can be hit under the skin in this area. If you accidentally “miss” and squirt insulin onto the skin, do not try to estimate loss and repeat the injection – simply wait until the next scheduled injection time. If you accidentally stick yourself with the needle, no diseases can be transmitted, and only minor discomfort will result.
Low blood sugar:
Low blood sugar can be caused by excessive insulin administration, poor food intake, or a change in the diabetes. Signs of low blood sugar include weakness, drooling, reduced responsiveness, wobbly gait, seizures, or coma. If any of these symptoms are seen, administer ________________ tablespoons of Karo® syrup by mouth. If the symptoms resolve, please feed a meal, and do not administer insulin until speaking with your veterinarian. If the symptoms do not resolve in 20 minutes, or are getting worse at any time, seek emergency medical attention for injectable glucose.
5. Recheck Visits:
Recheck visits should occur frequently in a newly diagnosed diabetic, and may require that your pet stay in the hospital for blood sugar evaluation over time. Please schedule your next recheck appointment for _________________________________________________________________________________________________________
6. When to Call:
Please call for assistance in the event of any of the following: Weakness, seizures, or any signs of low blood sugar, Vomiting or diarrhea, Loss of appetite, Ketones in the urine, Negative urine glucose, Increase in drinking, urination, appetite, or inappropriate urination