(1) Background: Among the chronic complications of type 2 diabetes mellitus, cancer
has become the leading cause of death in several countries. Our objective was to determine
whether prevalent type 2 diabetes mellitus is associated with a higher incidence of
cancer. (2) Methods: This study comprised a nationwide analysis conducted in Hungary.
The study population was divided into two groups: a type 2 diabetes mellitus group
vs. a non-diabetic group. The primary outcome was the risk related to overall cancer
incidence; a key secondary outcome was the overall incidence of cancer in distinct
study years; and a further outcome was the annual percent changes. (3) Results: The
odds ratio related to the overall incidence of cancer was 2.50 (95% confidence interval:
2.46–2.55, p < 0.0001) in patients with diabetes as related to non-diabetic controls.
The odds ratio was higher in males than in females [ORmales: 2.76 (2.70–2.82) vs.
ORfemales: 2.27 (2.22–2.33), p < 0.05 for male-to-female comparison]. The annual cancer
incidence rate declined in non-diabetic controls, but not in patients with diabetes
[−1.79% (−2.07–−1.52%), p < 0.0001] vs. −0.50% (−1.12–+0.10%), p = 0.0991]. Several
types of cancer showed a decreasing tendency in non-diabetic controls, but not in
patients with type 2 diabetes. (4) Conclusions: Type 2 diabetes is associated with
a higher risk of cancer. While the cancer incidence decreased for non-diabetic individuals
with time, it remained unchanged in patients with T2DM.
