Presence of prediabetes at baseline is associated with a 15% increased risk of cancer overall and when adjusting for BMI, which has already been linked to an increased risk for cancer, a prediabetes diagnosis can raise risks for certain cancers by 22%, according to meta-analysis of prospective cohort studies.
“Cancer should be considered as a potential complication of diabetes. The risk of cancer is increased even in intermediate stage blood glucose between normoglycaemia and overt diabetes mellitus. So periodic screening of abnormal blood glucose is important, not only for prevention of cardiovascular disease disease, but also for prevention of cancer,” Yuli Huang, MD, from the First People’s Hospital of Shunde, China, told Endocrine Today. “The risks of cancer were increased even when a lower fasting plasma glucose value of 5.6 to 6.9 mmol/L was used, according to the current American Diabetes Association definition of impaired fasting glucose. These findings support the lower threshold definition IFG proposed by the ADA, and highlight the clinical value of the early management of hyperglycemia to prevent cancer.”
The researchers looked at 16 prospective studies that included 891,426 participants with elevated blood glucose at baseline, 3 or more years of follow-up and an assessment for cancer development. The researchers standardized across the studies, all of which included adjusted RRs and 95% CIs.
Prediabetes, defined as impaired fasting glucose of either 5.6 mmol/L to 6.9 mmol/L or 6.1 mmol/L to 6.9 mmol/L (depending on the study) and/or impaired glucose tolerance, was associated with an overall increased risk for cancer (RR=1.15; 95% CI, 1.06-1.23). If looking only at IFG as a whole from 5.6 mmol/L to 6.9 mmol/L, the RR increased (RR=1.49; 95% CI, 1.05-2.11). Results were also significant for IFG from 6.1 mmol/L to 6.9 mmol/L (RR=1.11; 95% CI, 1.01-1.22), IGT (RR=1.25; 95% CI, 1.02-1.53) or combined IFG from 6.1 mmol/L to 6.9 mmol/L and/or IGT (RR=1.11; 95% CI, 1.02-1.22), researchers wrote.
Types of cancers developed did differ, with prediabetes associated with increased risks for cancer of the stomach/colorectum, liver, pancreas, breast and endometrium (all P<.05), but not with cancer of the bronchus/lung, prostate, ovary, kidney or bladder, they reported. Liver, endometrial and stomach/colorectal cancers had higher site-specific occurrence as well (P=.01).
Upon controlling for BMI, the researchers found that prediabetes was still associated with an increased risk for cancer (RR=1.22; 95% CI, 1.01-1.48).
The researchers suggest there are several mechanisms such as chronic oxidative stress or increased levels of insulin-like growth factor I that could contribute to this association.
“Lifestyle intervention (weight control, stop smoking and healthy diet, etc.) should be suggested earlier and recommended as the mainstay of treatment for prediabetes in the general population,” Huang said. “Dug treatment, such as metformin, maybe recommended in selected high-risk individuals, especially those with IGT or a combination of IGT and IFG. However, further studies are needed.”
Disclosure: The researchers report no relevant financial disclosures.