Objective: To investigate whether hyperglycemia is associated with increased cancer risk.
Research design and methods: In the Västerbotten Intervention Project of northern Sweden, fasting and postload plasma glucose concentrations were available for 33,293 women and 31,304 men and 2,478 incident cases of cancer were identified. Relative risk (RR) of cancer for levels of fasting and postload glucose was calculated with the use of Poisson models, with adjustment for age, year of recruitment, fasting time, and smoking status. Repeated measurements 10 years after baseline in almost 10,000 subjects were used to correct RRs for random error in glucose measurements.
Results: Total cancer risk in women increased with rising plasma levels of fasting and postload glucose, up to an RR for the top versus bottom quartile of 1.26 (95% CI 1.09-1.47) (P(trend) <0.001) and 1.31 (1.12-1.52) (P(trend) = 0.001), respectively. Correction for random error in glucose measurements increased these risks up to 1.75 (1.32-2.36) and 1.63 (1.26-2.18), respectively. For men, corresponding uncorrected RR was 1.08 (0.92-1.27) (P(trend) = 0.25) and 0.98 (0.83-1.16) (P(trend) = 0.99), respectively. Risk of cancer of the pancreas, endometrium, urinary tract, and of malignant melanoma was statistically significantly associated with high fasting glucose with RRs of 2.49 (1.23-5.45) (P(trend) = 0.006), 1.86 (1.09-3.31) (P(trend) = 0.02), 1.69 (0.95-3.16) (P(trend) = 0.049), and 2.16 (1.14-4.35) (P(trend) = 0.01), respectively. Adjustment for BMI had no material effect on risk estimates.
Conclusions: The association of hyperglycemia with total cancer risk in women and in women and men combined for several cancer sites, independently of obesity, provides further evidence for an association between abnormal glucose metabolism and cancer.