Top 5 Goals for Management of Diabetes Mellitus

Diabetes mellitus is a complex disease that affects dogs and cats, and although the pathologic mechanisms that lead to diabetes differ between the species, the clinical manifestations are similar.

Managing diabetes and controlling hyperglycemia can be challenging. Framing the disease in clinical context may help when treating an unregulated diabetic patient. Diabetes is a chronic disease, and expectations should be set for the pet owner, as chronic disease management is an active, lifelong effort. A long-term, goal-oriented approach to diabetes treatment is valuable when defining milestones and focusing efforts on specific clinical endpoints. Successful treatment requires effective communication and commitment to recommended treatment and monitoring. Prognosis is good when diabetes is appropriately managed. 

The goals discussed in this article overlap by necessity, as diabetes management requires an integrated clinical approach. Following are the author’s top 5 goals of care for managing patients with diabetes mellitus.

1. Consistent Daily Routines

Consistency is key and should include insulin administration, feeding schedule, and daily activity. For example, feeding the same diet in equal portions and avoiding treats between scheduled meals ensures the daily nutrient load and diet composition remain consistent. Exercise should be maintained rather than restricted to avoid potential (and generally unpredictable) effects on insulin requirements. Specific goals should be discussed with the owner and reminders communicated at follow-up appointments. In humans with diabetes, consistent daily diet, physical activity, and glycemic control routines are recommended¹; this can also benefit dogs and cats with diabetes. Variability is evident in glucose curves,^2,3 and, although some variability is biological in nature,⁴ consistent routines can help mitigate influences of daily life on overall glycemic control. 

Possible benefits of daily routines have not been specifically investigated, but surveys of owners with diabetic pets identified breaks in the normal routine (eg, boarding, using a pet sitter, onset of other illness) as having a negative impact on quality of life.^5,6 Quality of life was also a major factor in euthanasia decisions following diagnosis.⁷ Consistent daily routines lay the foundation for other management decisions, including insulin dose recommendations, diet or other interventions, and monitoring decisions.

2. Optimal Body Weight & Condition

Untreated diabetes is an aberrant nutritional state characterized by disordered carbohydrate, lipid, and protein metabolism.⁸ Some patients can appear thin or underconditioned before diabetes is clinically recognized, but others may appear obese or overconditioned. Effective insulin therapy to restore normal metabolism and efficient use of nutrients is needed in all patients diagnosed with diabetes.

Marked weight loss and reduced body condition in thin or underconditioned patients indicates a nutritional state akin to starvation; however, this is caused by metabolic disruptions from lack of insulin secretion or action at target tissues, not lack of sufficient nutrient intake. In severe cases, reduced carbohydrate utilization and unregulated lipolysis can lead to excess ketone production, which precipitates hyperketonemia and metabolic acidosis.⁸ Reversal is possible when insulin is again available to or accessible by tissues. Weight gain after initiation of insulin therapy is expected and is a positive indicator of insulin response.

Obesity is a risk factor for diabetes in cats,^9,10 as obesity decreases tissue insulin sensitivity, which is a major mechanism associated with type 2 diabetes in humans.⁹ Nutritional management to achieve optimal body weight in an obese diabetic patient requires weight loss, which poses unique challenges. Insulin treatment tends to lead to weight gain, which can exacerbate obesity. Synthetic insulins (eg, insulin glargine) can lead to undesired weight gain in humans and, anecdotally, in cats.<sup11 sup> 

Carefully considered dietary therapy is needed to achieve nutritional goals. Guidelines are available for dogs and cats but are primarily concerned with glycemia management recommendations.¹² A commercial diet formulated for adult dogs is suitable for most dogs with diabetes; the amount fed should be to maintain optimal weight. Adding extra dietary fiber or switching to a high-fiber diet can improve glycemic control in some dogs. A commercial low-carbohydrate diet is recommended for most cats with diabetes, based on reported success of these diets along with insulin therapy in inducing diabetes remission or achieving acceptable glycemic control in cats that do not enter remission.<sup13 sup> 

Judicious management of weight gain or loss and maintenance of optimal body weight require a comprehensive nutritional plan. Consultation with a veterinary nutritionist is suggested for difficult cases.

3. Management of Comorbid Disease

Even well-controlled diabetes is associated with high complication rates and frequent comorbid disease.^14,15 Middle-aged and older patients are at higher risk for diabetes and are frequently affected by comorbidities that may complicate management. All patients diagnosed with diabetes should be evaluated for complications. Common complications in dogs include cataracts and other ocular conditions.¹⁶ Diabetic polyneuropathy and other neurologic abnormalities have been documented in cats¹⁷ and dogs¹⁸; clinical recognition is more common in cats.

In addition to complications directly attributable to diabetes, various comorbid conditions can interfere with diabetes regulation or impact quality of life. Common comorbid diseases in dogs and cats include obesity,¹⁹ chronic pancreatitis,²⁰ and concurrent endocrinopathies (eg, hyperadrenocorticism in dogs, acromegaly in cats).¹² Hyperadrenocorticism in dogs is associated with insulin resistance and an insulin requirement that is larger than expected.¹² Acromegaly in cats has been recognized more frequently over the past decade and is a significant comorbidity that impairs diabetic control.²¹ Thyroid disorders, renal disease, neoplasia, and other diseases that occur more frequently in middle-aged and older patients are possible.¹² 

Common disorders, even relatively minor ones, can disrupt quality of life and cause management challenges.^5-7 Gingivitis, dental disease, dermatopathy, enteropathy, immune-mediated or neoplastic disease, chronic pain, and musculoskeletal disorders can affect daily routine, impact diabetes care, or require drug treatments that interfere with insulin efficacy.

4. Effective Monitoring Plan

The chronic nature of diabetes and the need for lifelong therapy should be emphasized with the owner. Most daily care is performed at home by the owner, and veterinary staff provides guidance and periodic evaluations to monitor health and maintain continuity of care. These periodic evaluations allow troubleshooting of issues with insulin therapy, assessment and encouragement for compliance, and reinforcement of treatment and management goals.

The recommended monitoring program should meet individual patient needs and owner abilities, circumstances, and treatment goals. Improving quality of life through consistent monitoring demonstrates the value of follow-up visits. Clinical and laboratory methods should be reviewed.^12,22 No single monitoring plan fits all patients, but combining several methods can be advantageous over any single method. Some methods, particularly random glucose measurement (ie, spot glucose checks), may be convenient but provide limited or misleading information about glucose and are not recommended for monitoring glycemic control or making insulin dose adjustments. 

Owner-reported clinical signs are subjective, insensitive indicators of hyperglycemia because patients may not exhibit major signs (eg, polyuria, polydipsia, weight loss) unless glucose disturbances are relatively severe (average blood glucose concentration, >250 mg/dL [13.9 mmol/L]).²² Direct (eg, interstitial glucose monitoring) or indirect (eg, glycated protein measurement) glucose assessment and clinical signs can provide a clearer picture of average daily glycemia. 

In a patient reported to be well at home with minimal clinical signs and no concerns for hypoglycemic episodes, routine follow-up may only include fructosamine and/or glycated hemoglobin assessment. Direct assessment of glucose using a glucose curve or interstitial glucose monitoring device is recommended in patients in which history or physical examination cause concerns for stability of glycemic control. This allows information to be gathered on an insulin time–action profile, which is used to detect hypoglycemia or guide changes in insulin therapy. 

The monitoring plan should adapt to the patient’s situation and include frequent (but not impractical or inconvenient) rechecks to identify recent changes in diabetic control. A well-controlled diabetic patient should be evaluated at least 3 to 4 times each year, with additional follow-ups when there are changes in insulin dose or type or onset of concurrent disease.²² 

Phone or email check-ins with the owner, periodic review of owner-generated data (eg, glucose curve data gathered at home), and a plan for addressing urgent concerns can be helpful. The goal for monitoring should be to establish a practical plan that addresses patient and owner needs and yields useful objective information.

5. Optimized Glycemic Control

The principal goal of diabetes treatment should be to control blood glucose, including optimizing glycemic control and avoiding hypoglycemia.^12,13,23 Although remission is also a goal in all cats, it is most achievable in newly diagnosed cats. 

Insulin is the principal drug used to address hyperglycemia in most cats and dogs. No single insulin type has an intrinsic advantage over another for controlling glucose, but some products have regulatory approval for use in both species, and some formulations are more suited to particular clinical scenarios. For example, ultrashort- and short-acting formulations are usually reserved for in-clinic and emergency glucose control.^24,25 For at-home daily use, guidelines based on published trials and clinical experience recommend administration of an intermediate (neutral protamine Hagedorn insulin or lente insulin) or long-acting (protamine zinc insulin or insulin glargine) formulation every 12 hours in dogs¹² and administration of a long-acting formulation every 12 hours in cats.^12,13,23 It is important to be familiar with frequently used insulins and to educate owners on proper administration, handling, and storage of the recommended insulin product. After initiating insulin treatment, serial monitoring of the patient’s response should guide dose adjustments to achieve glycemic control. 

Hypoglycemia is the most frequent and dangerous complication associated with insulin treatment. Owner education is important for decreasing the risk for hypoglycemia, and all owners should be trained to recognize and treat hypoglycemia.

Changes in diet may help establish glycemic control in some patients.^12,13 Although diet and other lifestyle changes have been shown to be effective in managing type 2 diabetes in humans, diet is not recommended as the sole treatment in dogs and cats. Dogs are almost always insulinopenic and, thus, insulin-dependent at diagnosis. Cats with diabetes may have detectable insulin levels at diagnosis, but insulin treatment is needed regardless to reverse glucose toxicity. Various oral hypoglycemic drugs and other drugs with glucose-lowering actions are used to treat humans with type 2 diabetes.<sup26 sup> 

Diet combined with an alpha-glucosidase inhibitor that reduces glucose absorption from the GI tract has been studied in dogs and cats.^27,28 Glipizide, a sulfonylurea drug that directly stimulates insulin release, and glucagon-like peptide 2 analogs, which mimic the insulin-secreting actions of the incretin hormone glucagon-like peptide 2, have been studied in cats with diabetes,^29,30 but these drugs are not widely used and have limited roles in treatment of canine and feline diabetes.

Optimal glycemic control can be a moving target in dogs and cats, depending on how control is defined. Studies that examine insulin efficacy and safety use several methods to assess glycemic control, including assessing clinical signs, maintaining glycated proteins in a target range, and determining the insulin time–action profile (ie, glucose curve).^31-38 Each assessment method has advantages and disadvantages, and no single method is clearly superior. Results of any monitoring test should be considered based on clinical assessments, including owner impressions about the patient’s health; therefore, combined assessments (usually clinical signs and at least one additional assessment) are recommended to assess glycemic control.^12,22