Use of C-peptide and homeostasis model assessment of insulin resistance to assess insulin resistance in dogs
Chutirat Torsahakul, Watchareewan Rodprasert, Kittiya Simphaisarn, Nawasin Kanthathong, Sasiprapa Kaonarsanga, Nawat Sannamwong, Saharuetai Jeamsripong, Chenphop SawangmakeAbstract
Background
Insulin resistance (IR) is a common complication in diabetic dogs, impairing glycemic control and causing metabolic dysfunction.
Hypothesis/Objectives
To assess the utility and determine cutoff values of C-peptide, homeostasis model assessment of IR by C-peptide (HOMA-IR by C-peptide), HOMA-IR by C-Peptide version 2 (HOMA-IRCP2), and homeostasis model assessment 2 of IR (HOMA2-IR) as diagnostic tools for detecting IR and identifying factors related to IR in dogs with diabetes.
Animals
Seventy-six dogs were enrolled from a referral center and classified into 4 groups: healthy dogs (Healthy group, n = 17), pre-diabetes mellitus (PreDM, n = 11), insulin-dependent diabetes mellitus (IDDM, n = 20), and insulin-resistant diabetes mellitus (DMIR, n = 28).
Methods
A cross-sectional prospective study. Blood samples were collected from dogs from which food was withheld and analyzed for glucose, C-peptide, and other metabolic indicators. HOMA-IR by C-peptide, HOMA-IRCP2, and HOMA2-IR were determined and compared across groups.
Results
The DMIR group exhibited the highest C-peptide and HOMA-IR by C-peptide, HOMA-IRCP2, and HOMA2-IR. Receiver Operating Characteristic curve analysis demonstrated that C-peptide, HOMA-IR by C-peptide, HOMA-IRCP2, and HOMA2-IR identified IR, with area under curve of 0.843 (95% CI, 0.756-0.930), 0.897 (95% CI, 0.819-0.975), 0.893 (95% CI, 0.812-0.973), and 0.789 (95% CI, 0.686-0.893), respectively (P < 0.001). A cutoff level of ≥0.7 ng/mL for C-peptide and ≥120 for HOMA-IR by C-peptide demonstrated the highest sensitivity (92.9%), whereas ≥1.65 for HOMA-IRCP2 showed the highest specificity (97.9%).
Conclusions and clinical importance
C-peptide, HOMA-IR by C-peptide, HOMA-IRCP2, and HOMA2-IR are promising, non-invasive indicators of IR. Early identification of IR using these markers might improve clinical outcomes.