Glycated hemoglobin, diabetes treatment and cancer risk in type 2 diabetes. A case-control study.

INTRODUCTION

Type 2 diabetes is associated with an increased risk of some types of cancer. Diabetes treatment may also modify cancer risk.

OBJECTIVE

The aim of this retrospective, case-control study was to assess whether HbA1c level and use of anti-diabetic drugs are associated with cancer development in a diabetic population.

MATERIALS AND METHODS

The case group consisted of 53 patients who developed cancer after diagnosis of diabetes. They were compared with 53 diabetic subjects without cancer, strictly matched to a case group by age and gender. In both groups - apart from HbA1c and diabetes treatment - demographic data, smoking habits, comorbidities, BMI, diabetes duration, use of aspirin, antihypertensive and hypolipemic drugs were also analyzed.

RESULTS

Patients with cancer had a significantly higher mean HbA1c value compared with the control group, 7.83±1.26% vs. 7.30±1.08%, respectively (p=0.022). The distribution of patients in four HbA1c categories (<7.0, 7.0-7.9, 8.0-8.9 and ≥9.0%) was significantly different between the two groups (p=0.031). The probability of cancer was higher among patients with HbA1c value ≥8.0 % OR 3.160 (95% CI 1.342-7.440), p=0.013, and lower among patients using metformin, OR 0.228 (95% CI 0.083-0.633), p=0.006. The number of insulin users, insulin dose, duration of insulin treatment, and use of other anti-diabetic drugs were not significantly different between the two groups. Also, no significant differences were found between the two groups regarding other variables.

CONCLUSIONS

The presented case-control study indicated an important role of metabolic control and confirmed the protective role of metformin in reducing cancer risk among patients with type 2 diabetes. Contrary to other studies, insulin use was not associated with a higher risk of cancer. Other anti-diabetic drugs appeared to have a neutral impact on cancer development.