Malignancy incidences by glycemic control among diabetic patients

Dawn of a new era of diabeto-oncology

Pathways of the mutual relationship between diabetes and cancer.

Development of malignancies and changes in time-dependent hemoglobin A1c among a nondiabetic population: longitudinal analysis

BACKGROUND

The fluctuation of hemoglobin A1c (HbA1c) and changes in health habits over time was not considered in previous studies. The aim of this study was to evaluate the time-sequenced association between malignancy incidence and HbA1c with a longitudinal study design using repeated measurements of HbA1c.

METHODS

A retrospective longitudinal study was conducted at a large teaching hospital in Tokyo, Japan, from 2005 to 2016. All participants who underwent voluntary health check-ups at the hospital were included. Our outcomes were the development of malignancy. We compared these outcomes using HbA1c categories. Longitudinal analyses were conducted with a mixed effects model in which time-dependent HbA1c measurements were applied to consider fluctuations in HbA1c levels, adjusted for covariates.

RESULTS

A total of 77,385 nondiabetic participants were included in the study; the mean age was 44.7 and 49.4% of participants were male. During a median follow-up of 1588 (interquartile range 730-2946) days, 4506 (5.8%) participants developed malignancies. The relationship between future malignancies and HbA1c was U-shaped; both the lower HbA1c groups (OR 1.31, 95% CI 1.17-1.46 for < 5.0%) and the higher HbA1c group (OR 1.87, 95% CI 1.03-3.39 for ≥ 7.5%) had significantly higher odds ratios compared to the 5.5-5.9%. The lowest HbA1c was associated with higher odds of breast cancer (OR 1.5, 95% CI 1.21-1.86) and female genital cancer (OR 1.57, 95% CI 1.04-2.37).

CONCLUSIONS

Our study found a U-shaped association between HbA1c and future malignancies among nondiabetic people but did not find additional risk at the prediabetic level. Low HbA1c may be associated with the incidence of breast cancer and female genital cancer.

Visit-to-Visit Hemoglobin A1c Variability Is Associated With Later Cancer Development in Patients With Diabetes Mellitus

PURPOSE

Recent studies have shown that patients with diabetes mellitus have a higher risk of tumorigenesis. However, the effect of glycemic variability on tumorigenesis among diabetic patients has not been well investigated. Hence, we performed a retrospective cohort study to analyze the effect of visit-to-visit hemoglobin A1c (HbA1c) variability and later onset of malignancies.

METHODS

This study included 2640 patients with diabetes mellitus 50 years or older. To analyze visit-to-visit glycemic activity, we calculated intrapersonal SD of all recorded HbA1c and used SD-HbA1c as a measure of glycemic variability. Because the number of individual visits varied, we divided SD-HbA1c by visit times in order to adjust for the potential influence of visit time difference between individuals. Patients were divided into quartiles according to their HbA1c variability, and Cox regression models were used to evaluate the association between glycemic variability and later onset of tumorigenesis.

RESULTS

Three hundred thirty patients (12.5%) developed malignancy during follow-up. The median follow-up period was 1511 days (4.1 years; interquartile range, 2487.5 days). Relative to the group with the lowest glycemic variability (first quartile), the groups with higher glycemic variability showed a dose-dependent association with tumorigenesis. The odds ratios for the second, third, and fourth quartiles were 1.20 (95% confidence interval, 0.88-1.65), 1.43 (1.02-2.00), and 2.19 (1.52-3.17), respectively. The mean HbA1c and diabetes mellitus duration periods were not significantly associated with tumorigenesis. This result was consistent when limiting the number of covariates.

CONCLUSIONS

These results demonstrated that visit-to-visit HbA1c variability is a potential risk factor for later tumorigenesis. The association may be mediated by oxidative stress or hormone variability. Routine cancer screening may be suggested for diabetic patients with unstable glycemic control.