Background: Gestational diabetes is a form of hyperglycemia that emerges during pregnancy and may be associated with an elevated risk of breast cancer. Although numerous studies have explored the relationship between gestational diabetes and breast cancer, the findings have been inconsistent. This research was conducted to examine the link between gestational diabetes and breast cancer.

Methods: This case-control study was conducted on 353 women. The records of women referred to the oncology departments with a diagnosis of breast cancer were used as the case group(n=176), and the records of women referred without a cancer diagnosis were used as the control group(n=177). The inclusion criteria for the case group were: a history of breast cancer, age between 30 and 60 years, being married, history of deliveries, and no prior history of breast cancer before pregnancy. A researcher-designed checklist was used for data collection. Descriptive statistical tests, independent t-test, chi-square, and regression analysis were used to analyze the data.

Results: The mean ages in the case and control groups, were 45.80 ± 8.17 and 44.71 ± 9.33 years, respectively. Based on the logistic regression analysis, gestational diabetes was not a significant predictor. However, it was demonstrated that with each one-year increase in age at first pregnancy, the odds of breast cancer decrease by 10%, and breast cancer was not a significant predictor of gestational diabetes.

Conclusion: The results of this investigation indicate that no statistically significant link exists between gestational diabetes and the development of breast cancer of breast cancer.