Clinical Case Study: Feline Diabetes

Diabetes mellitus
12-year-old, neutered male domestic shorthair, Okun
Submitted by Fred L. Metzger, DVM, DABVP, MRCVS, Metzger Animal Hospital, State College,
Pennsylvania
Presenting reason
Okun was presented for evaluation of polyuria/polydipsia (PU/PD) and possible
weight loss.
History
Okun had a recent history of increased urination and drinking, though the
owner said that it was less obvious the last few days. His stool had been loose
for several days, but a recent fecal examination was negative. There was no
reported coughing, sneezing or vomiting. He is an indoor-only cat and is
current on all appropriate vaccines. His activity score is 9/10, with 10 being a
normal activity level for his age as perceived by his owners.
Physical examination
On physical examination, Okun was quiet, alert, responsive and hydrated. Mucous membranes were
pink and the capillary refill time (CRT) was <2 seconds. Temperature was 102o F and pulse and
respiration were normal. He was overweight with mild muscle mass loss (body condition score [BCS]
of 4/5). Thoracic auscultation, abdominal palpation and thyroid palpation were unremarkable.
Differential diagnoses
Diabetes mellitus, acute or chronic renal disease, hyperthyroidism, diabetes insipidius,
hyperadrenocorticism and psychogenic polydipsia with medullary washout are potential differentials
for the reported PU/PD.
Diagnostic plan
A minimum database, including a complete blood count (CBC), chemistry profile, complete urinalysis
and total T4, was recommended to screen for underlying/concurrent metabolic, endocrine,
inflammatory and infectious disease. Abdominal radiographs and urine culture were strongly
recommended, but the owners declined, citing financial constraints.
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Laboratory data
Hematology
Erythrogram—No significant abnormalities were present. No morphologic abnormalities were noted on
blood film review.
Leukogram—The potential of a glucocorticoid influence (“stress”) must be considered even with all
leukocyte parameters within reference interval limits; lymphocyte counts less than 1,000/µL in the cat
are strongly supportive of a glucocorticoid influence. No morphologic abnormalities were noted on
blood film review.
Thrombogram—No significant abnormalities were present. No morphologic abnormalities were noted
on blood film review.
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Chemistry
Glucose—The finding of a considerable hyperglycemia (combined with glucosuria noted below and the
clinical findings) strongly supported a diagnosis of diabetes mellitus. Because of the occurrence of
stress hyperglycemia, a fructosamine level is often used to confirm a diagnosis of diabetes in feline
patients but was not considered necessary in this case.
Electrolyte
Electrolytes/Acid-base panel—Although all electrolytes are within reference interval limits, there are
mild but potentially significant changes supportive of an underlying metabolic disturbance. Typically
sodium and chloride follow one another extremely closely during hydration status changes. In this
case, chloride is mildly low relative to sodium, which is commonly observed with metabolic alkalosis.
Situations where there is loss of chloride during metabolic alkalosis include loss of hydrochloric acid
(HCl) during gastric vomiting or chloride sequestration in the upper gastrointestinal tract. The pattern
of low chloride relative to sodium supports a mild simple metabolic alkalosis. Since there was no
observation of vomiting and the more typical acid-base disturbance seen with diabetes mellitus is
metabolic acidosis, reevaluation of the electrolyte/acid-base panel is warranted once the cat is
stabilized and the diabetes is under control.
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Urinalysis
The presence of glucosuria supports diabetes mellitus. The increased RBC was considered to be
iatrogenic (due to cystocentesis). A urine culture and sensitivity was recommended but declined by
the owner.
Total T4
The total T4 concentration was 2.7 µg/dL (reference interval: 0.8–4.7 µg/dL). If hyperthyroidism had
been suspected, further evaluation with a free T4 would have been indicated.
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Therapeutic plan and case outcome
Okun was discharged on lente insulin (Vetsulin®, Merck) administered subcutaneously every 12 hours
and a low-carbohydrate diet. The owner was given careful and thorough instructions on how to
administer insulin as well as proper insulin care and handling. This was reinforced with detailed
handouts. While not available when Okun was diagnosed, owners can now visit the PetHealth
Network® for educational materials and instructional videos on diabetes mellitus. Follow-up evaluation,
including fructosamine determination, was done in 3 weeks (see below). The owner reported some
improvement in PU/PD. Based on this evaluation, the dose of insulin was increased.
Home | Lab Services | Telemedicine | Reference
+
Pro
2009
OCT 3
+
OKUN
2011
10/3/2009 (Order Received)
10/3/2009 @ 10:53 pm (Last Updated)
Fructosamine
Hemolysis Index
538
o
o
IDEXX Reference Laboratories
Show Details
191 - 349 µmol/L
N
Interpretive Guidelines for Diabetic Patients:
DOG:
300 - 350
350 - 400
400 - 450
>450
<250
CAT:
300 - 350
350 - 400
400 - 450
>450
<250
Glycemic Control:
Excellent
Good
Fair
Poor
Prolonged Hypoglycemia
Serum fructosamine concentrations are used in diabetic patients as a
marker of mean blood glucose concentration during the preceding 2 to
3 weeks. The higher the average blood glucose concentration over this
time, the higher the serum fructosamine concentration, and vice versa.
Since our serum fructosamine concentrations correlate well with the
endocrinology lab at UC Davis, interpretive ranges noted above have
interpretation.
Results for fructosamine may be incresed up to 150% by the presence of
hemolysis. Please note as of June 29, 2006, these guidelines have been
same method of analysis.
Reference: Feldman and Nelson; Canine and Feline Endocrinology and
Reproduction. 3rd. ed. W.B. Saunders Co., 2004.
Thereafter Okun’s insulin dosage was adjusted based on periodic evaluations that included
fructosamine determination (see below).
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Home | Lab Services | Telemedicine | Reference
+
Pro
2013
AUG 8
2011 6
AUG
FEB 15
FEB 13
2012
+
OKUN
JUN 14 MAR 18 MAR 15
FEB 14
FEB 10
2011
JUL 29
JUL 27
FEB 18
2010
DEC
Trending
Jul ’09
8/8/2013 (Order Received)
8/8/2013 @ 11:48 am (Last Updated)
Fructosamine
Hemolysis Index
311
a
a
IDEXX Reference Laboratories
191 - 349 µmol/L
N
Jan ’11
Apr ’12
Aug ‘13
Fructosamine
356
c
N
0
Interpretive Guidelines for Diabetic Patients:
CAT:
300 - 350
350 - 400
400 - 450
>450
<250
6/14/12
350
b
N
DOG:
300 - 350
350 - 400
400 - 450
>450
<250
2/5/13
Show Details
Glycemic Control:
Excellent
Good
Fair
Poor
Prolonged Hypoglycemia
Serum fructosamine concentrations are used in diabetic patients
as a marker of mean blood glucose concentration during the
preceding 2 to 3 weeks. The higher the average blood glucose
concentration over this time, the higher the serum fructosamine
concentration, and vice versa.
Results for fructosamine may be incresed up to 150% by the
presence of hemolysis.
Reference: Feldman and Nelson; Canine and Feline Endocrinology
and Reproduction. 3rd. ed. W.B. Saunders Co., 2004.
Fructosamine
0
Jul ’09
Jan ’11
Apr ’12
Aug ‘13
Further discussion
Diabetes mellitus is a relatively common endocrine disorder in cats. One source puts the incidence at 1
in 200.1 While there is no breed predilection, male cats appear predisposed. The mean age is 10 years
and about 75% of cats are 8–13 years of age.1 Clinical signs in both dogs and cats include PU/PD,
polyphagia and weight loss.2 The assessment of the diabetic patient should include an evaluation of
overall health, identification of complications and/or concurrent disease as well as interfering
conditions and risk factors. For this reason, a complete laboratory assessment is necessary to
thoroughly evaluate these patients. The recommended diagnostic testing for animals with suspected
or confirmed diabetes mellitus and includes a CBC, biochemical profile, complete urinalysis and urine
culture.
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Most veterinary endocrinologists recommend placing uncomplicated feline diabetics on twice daily
injections of a long-acting insulin preparation. Unless contraindicated by another condition, diabetic
cats are placed on a low-carbohydrate diet. The majority of diabetic cats require insulin twice a day to
provide the best control of blood glucose levels and increase the chances of remission. It is
recommended that close monitoring and adjustment of the insulin dose occur in the first few months
of treatment, because many cats will achieve diabetic remission within this time.
Fructosamines are stable complexes of serum carbohydrates and proteins that are produced by an
irreversible, nonenzymatic glycosylation of proteins, and they are related to circulating glucose
concentration. A fructosamine level assesses the average blood glucose concentration over the
previous 2–3 weeks in canines and felines. Determination of fructosamine levels has become integral
part of the monitoring of insulin therapy of diabetes mellitus in both dogs and cats, and in fact, it is
included in the current AAHA guidelines for this disorder. Fructosamine levels are determined every 2–
4 weeks during the initial regulation of the diabetic patient and then every 3–6 months during longterm management. Whether or not to alter the dosage of insulin is determined by evaluating the
fructosamine level in conjunction with the patient’s clinical signs and results of the blood glucose
curve. Frequent communication between the veterinary healthcare team is critical to the successful
care of a diabetic patient, as are regularly scheduled recheck examinations during which clinical signs
and body weight are assessed.
References
1. Greco DS. Diabetes mellitus without complications—cats. In: Tilley LP, Smith FWK, eds.
Blackwell’s Five-Minute Veterinary Consult: Canine and Feline. 5th ed. Ames, IA: Wiley-Blackwell;
2011:366–367.
2.
Rand JS. Feline diabetes mellitus. In: Mooney CT, Peterson ME, eds. BSAVA Manual of Canine and
Feline Endocrinology. 4th ed. Gloucester, England: British Small Animal Vet Assoc; 2012:133–147.
Recommended reading
AAHA Guidelines
Côté E. Clinical Veterinary Advisor: Dogs and Cats. St Louis, MO: Mosby; 2007.
Latimer KS, ed. Duncan & Prasse’s Veterinary Laboratory Medicine: Clinical Pathology. 5th ed. Ames,
IA: Wiley-Blackwell; 2011.
The recommendations contained in these educational materials are intended to provide general
guidance only. As with any diagnosis or treatment, you should use clinical discretion with each patient
based on a complete evaluation of the patient, including history, physical presentation and complete
laboratory data. With respect to any drug therapy or monitoring program, you should refer to product
inserts for a complete description of dosages, indications, interactions and cautions.
Vetsulin is a registered trademark of Intervet Inc., a subsidiary of Merck & Co., Inc.
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