Early-Stage Canine Diabetes: Recognizing the Missed Therapeutic Window

Diabetes mellitus in dogs is a chronic endocrine disease characterised primarily by insulin deficiency resulting from pancreatic β-cell loss. Comprehensive reviews of canine diabetes consistently describe the condition as analogous to insulin-dependent diabetes in humans, with most affected dogs requiring lifelong exogenous insulin therapy for survival and metabolic control¹. Clinical diagnosis is commonly established only after sustained hyperglycaemia and classical signs such as polyuria, polydipsia, polyphagia, and weight loss become evident.¹ This pattern of presentation suggests that underlying metabolic disturbances often precede overt disease recognition. 

Early Metabolic Disturbance and Disease Progression 

Although remission is not considered a realistic outcome in canine diabetes, the disease does not appear to emerge abruptly. Evidence summarised in recent veterinary literature indicates that β-cell dysfunction and altered glucose–insulin dynamics develop progressively, even if they are not routinely measured in early clinical stages.¹ This gradual progression explains why many dogs are diagnosed only once metabolic compensation has failed, rather than during earlier phases of dysregulation. 

The contribution of insulin resistance in dogs is variable but clinically relevant. While insulin resistance is not the dominant mechanism of canine diabetes, it may coexist with insulin deficiency, particularly in dogs with obesity or concurrent endocrinopathies¹. This dual influence complicates interpretation of glucose values and highlights the need for metabolic assessment beyond isolated glucose measurements. 

Use of HOMA Indices in Metabolic Assessment 

The Homeostasis Model Assessment (HOMA) index has been investigated as a method to estimate insulin resistance (HOMA-IR) and β-cell function (HOMA-β) using fasting glucose and insulin concentrations. A 2025 systematic review evaluating the application of HOMA in dogs and cats concluded that these indices could provide insight into metabolic status, particularly in distinguishing insulin resistance from primary insulin deficiency². 

The review emphasised that, in dogs, elevated HOMA-IR values may reflect increased metabolic demand or concurrent insulin resistance superimposed on β-cell dysfunction rather than a reversible pre-diabetic state². Importantly, the authors noted that HOMA indices should not be used as diagnostic criteria for diabetes but may serve as adjunctive tools when interpreted alongside clinical findings and standard laboratory results². The absence of validated species-specific cut-offs necessitates cautious application in referral and advanced practice settings. 

Continuous Glucose Monitoring and Glycaemic Variability 

Advances in glucose monitoring technology have enabled assessment of glycaemic variability over time rather than reliance on single-point measurements. An open-access study published in BMC Veterinary Research evaluated a real-time continuous glucose monitoring system (RT-CGMS) in diabetic dogs and demonstrated that continuous monitoring captures substantial glucose fluctuations during routine daily activity³. 

In this study, interstitial glucose measurements obtained via RT-CGMS showed a strong correlation with contemporaneous blood glucose values measured using portable glucometers, supporting analytical validity.³ The continuous data revealed frequent hyperglycaemic periods and marked variability across the monitoring duration, findings that would not be apparent from intermittent sampling alone.³ Although the study focused on dogs with established diabetes, it provides evidence that CGMS is capable of characterising dynamic glucose patterns relevant to advanced clinical management. 

Implications for Referral and Advanced Practice 

Taken together, the current evidence supports a model in which canine diabetes progresses through measurable metabolic disturbance before classical diagnostic thresholds are crossed^1,2. While early detection does not alter the ultimate need for insulin therapy, identifying metabolic instability earlier may allow clinicians to contextualise glycaemic trends, evaluate concurrent insulin resistance, and anticipate challenges in long-term regulation^2,3. 

In referral settings, combining fasting insulin-based indices with longitudinal glucose assessment may enhance interpretation of complex cases, particularly where glycaemic control is inconsistent or disproportionate to insulin dosing^2,3. 

Clinical Takeaways 

Available evidence confirms that canine diabetes is fundamentally an insulin-deficient disease with progressive β-cell loss.¹ Adjunctive metabolic tools such as HOMA indices can contribute to assessment of insulin resistance and β-cell function when used cautiously and in conjunction with clinical evaluation.² Continuous glucose monitoring has been shown to accurately reflect glucose variability and glycaemic patterns in diabetic dogs, offering additional insight beyond single glucose measurements in advanced practice contexts.³ 

When to Reconsider or Refer 

Referral-level assessment is supported when dogs demonstrate persistent hyperglycaemia with unexplained variability, poor response to appropriate insulin therapy, or suspected concurrent endocrine disease. In such cases, integrating fasting insulin-based indices and continuous glucose monitoring may assist in clarifying the metabolic contributors to dysregulation and guiding more individualised management strategies.¹–³ 

 References  

1. Mendes Junior AF, Cabral NG, Roboredo M. Diabetes mellitus in dogs and cats: a literature review. Res Soc Dev. 2025;14(11):e214141150176. Available from: https://rsdjournal.org/rsd/article/view/50176 

2. Hrițcu LD, Boghian V, Pavel G, Hrițcu TD, Spataru A, Burtan LC, et al. Application of the HOMA index in diabetic dogs and cats: a systematic review of current evidence. Appl Sci. 2025;15(19):10342. Available from: https://www.mdpi.com/2076-3417/15/19/10342 

3. Xi J, Yang H, Zhang Q, Yang S, Ping F, Fang X. Glucose monitoring intelligent tracking system for remote glycaemic assessment in diabetic dogs: a novel approach. BMC Vet Res. 2025;21:354. Available from: https://bmcvetres.biomedcentral.com/articles/10.1186/s12917-025-04809-6