Aims of Management
Treatment of diabetes mellitus (DM) involves insulin along with dietary modification. Goals for treatment include eliminating clinical signs by controlling blood glucose levels below the renal threshold for as much of a 24-hour period as possible and avoiding clinically significant hypoglycaemia.1 This is facilitated through determination of the optimal insulin type and dose, maintenance of appropriate body weight and appetite, as well as management or treatment of comorbidities.
Monitoring Tools
These include performance of blood glucose curves (BGC), monitoring of glucosuria, measuring fructosamine, clinical signs and weight. Results from these modalities may also yield conflicting information.2
1. Clinical Signs and Weight
An owner log would be useful to keep track of appetite, water consumption, and urination habits. Clinical hypoglycemia should also be recorded. A physical examination including measurement of body weight should be performed at each visit.
2. Urine Glucose
Urine glucose measurements can be helpful but remain only an indication of the BG over the time interval that the bladder was filling, and relying solely on urine glucose measurements is not encouraged. Persistence of trends may also be more significant than single measures unless ketonuria is detected.
3. Glycosylated Proteins
Use of glycosylated proteins for monitoring diabetic patients includes serum fructosamine and glycosylated haemoglobin. Fructosamine forms from the irreversible binding of glucose to serum proteins, mainly albumin. Fructosamine concentrations are proportional to the blood glucose levels as well as affected by the half-life of albumin. It reflects glucose levels over the 1–2 weeks before sampling. However, several factors (other than plasma glucose concentration) affect fructosamine concentration, including hypoproteinemia, hyperlipidemia, and azotemia.3
Glycosylated haemoglobin (HbA1c) is a haemoglobin product with glucose attached to its N-terminal amino acid valine. Glycosylation is irreversible, and concentration of HbA1c within the circulation is approximately 2–3 months—the lifespan of the red blood cell. Therefore, it may be a consideration for long-term control of stable diabetics, especially when the patient has comorbidities that affect turnover of fructosamine. Renewed interest has been shown in monitoring HbA1c, as, unlike fructosamine, it is associated with outcomes and therapeutic targets in humans.4,5
4. Blood Glucose Curves
A BGC should be performed on the introduction of a new type of insulin; when deciding on a dose change; one to two weeks after a dose change; three monthly in stable diabetics; when clinical signs of DM recur; or when hypoglycaemia is suspected. The goals of a BGC are to determine the duration of action of the insulin, the glucose nadir, and the range of BG throughout the day. Ideally, we aim for the duration of insulin effect to be 10–12 h, BG nadir 100–150 mg/dl for the long-term diabetic pet, and average BG less than 250 mg/dl over that 10–12 h.1,5 However, while these parameters are ideal, AAHA defines goals of diabetic monitoring to be control of clinical signs while avoiding hypoglycaemia.1 Also, there appears to be a considerable variation in serial BGCs in diabetic dogs, making curve interpretation and decision-making difficult.6 Therefore, glycaemic control should not be based solely on these numbers. The AAHA recommends home BGCs where possible, as they are expected to be representative of the patient’s activity, and eliminate stress and associated influences.
BG monitoring should be based on methods validated for dogs. The AlphaTRAK 2 is the glucometer recommended for use in veterinary patients, as it has been calibrated in dogs and cats.1,7 The preference is to use whole blood with this glucometer to improve accuracy, rather than plasma or serum.8 The use of continuous and flash glucose monitoring systems have also been described.9,10 These devices allow measurement of interstitial glucose and have shown good correlation to blood glucose within specific ranges.8,9 These systems provide advantages of allowing more frequent measurements, not requiring patient restraint and phlebotomy, and decreased cost to the client. It also improves the ease at which home glucose curves are to be performed.
References
1. Behrend E, Holford A, Lathan P, Rucinsky R, Schulman R. AAHA diabetes management guidelines for dogs and cats. J Am Anim Hosp Assoc. 2018;54:1–21. doi 10.5326/JAAHA-MS-6822.
2. Briggs CE, Nelson RW, Feldman EC, Elliot DA, Niel LA. Reliability of history and physical examination findings for assessing control of glycemia in dogs with diabetes mellitus: 53 cases (1995–1998). J Am Vet Med Assoc. 2000;217:48–53.
3. Danese E, Montagnana M, Nouvenne A, Lippi G. Advantages and pitfalls of fructosamine and glycated albumin in the diagnosis and treatment of diabetes. J Diabetes Sci Technol. 2015;9:169–176. doi: 10.1177/1932296814567227.
4. Ramsey A, Goemans AF, Spence SJ. Novel HbA1c assay for the monitoring of canine diabetes. In: ACVIM Forum Proceedings; National Harbor, MD; 2017:1079–1080.
5. Krecic M. Monitoring of diabetic patients: could we do better? In: ACVIM Forum Proceedings; National Harbor, MD; 2017:1172–1173.
6. Fleeman LM, Rand JS. Evaluation of day-to-day variability of serial blood glucose concentration curves in diabetic dogs. J Am Vet Med Assoc. 2003;222:317–321.
7. Cohen TA, Nelson RW, Kass PH, Christopher MM, Feldman EC. Evaluation of six portable blood glucose meters for measuring blood glucose concentration in dogs. J Am Vet Med Assoc. 2009;235:276–280.
8. Behrend EN, Suchowersky ND, Carlson EA, Lee HP. Comparison between glucose measurements in canine whole blood, serum, and plasma. J Vet Intern Med. 2017;31:1271–1272.
9. Corradini S, Pilosio B, Dondi F, Linari G, Testa S, Brugnoli F, Gianella P, Pietra M, Fracassi F. Accuracy of a flash glucose monitoring system in diabetic dogs. J Vet Intern Med. 2016;30:983–988.
10. Wiedmeyer CE, DeClue AE. Continuous glucose monitoring in dogs and cats. J Vet Intern Med. 2008;22:2–8.