Hemoglobin A1c is a retrospective indicator of denning in polar bears (Ursus maritimus)
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Abstract
The nutritional health of polar bears (Ursus maritimus) is tied to reproductive success, and fasting status can be used to infer recent reproductive history. However, the methods currently used to determine denning and fasting status have their limitations. We examined hemoglobin A1c (HbA1c), an integrative metric of average blood glucose levels over recent months, in free-ranging Southern Beaufort Sea polar bears to assess its usefulness in determining reproductive status and fasting. We compared HbA1c between bears recently in maternity dens that included spring-captured females that were accompanied by cubs-of-the-year (n = 38), and non-denned bears that included spring-captured females that were accompanied by 1- or 2-yr-old cubs (n = 39). We predicted that HbA1c would be higher in denned females compared to non-denned females, due to the combined effects of increased circulating glucose associated with insulin resistance from fasting and gestation, as well as the energy mobilization required during early lactation. HbA1c was measured in Polar Bear whole blood samples using an enzymatic assay for quantifying HbA1c and expressed as the percentage of glycated hemoglobin over total hemoglobin. Denned females had higher mean HbA1c (x̅ 4.70%, 95% CI = 4.54%, 4.86%) than non-denned (x̅ 4.38%, 95% CI = 4.23%, 4.53%, P = 0.005). We trained a binary logistic regression model to classify the probability of recent prior denning based on HbA1c and glucose, and the model classified denning with 75% accuracy. HbA1c can be used as an effective tool for determining denning history and could have implications for monitoring reproductive success.
Suggested Citation
Teman, S.J., Atwood, T.C., Laidre, K.L., Virgin, E.E., Rode, K.D., Rispoli, L.A., and Curry, E., 2025, Hemoglobin A1c is a retrospective indicator of denning in polar bears (Ursus maritimus): Journal of Mammalogy, v. 106, no. 5, p. 1167-1177, https://doi.org/\10.1093/jmammal/gyaf033.
ISSN: 1545-1542 (online)
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Hemoglobin A1c is a retrospective indicator of denning in polar bears (Ursus maritimus) |
| Series title | Journal of Mammalogy |
| DOI | \10.1093/jmammal/gyaf033 |
| Volume | 106 |
| Issue | 5 |
| Publication Date | June 27, 2025 |
| Year Published | 2025 |
| Language | English |
| Contributing office(s) | Alaska Science Center Ecosystems |
| Description | 11 p. |
| First page | 1167 |
| Last page | 1177 |
| Country | Canada, United States |
| State | Alsaka, Northwest Territories, Yukon |
| Other Geospatial | South Beaufort Sea |