Getting Closer to Type 2 Diabetes Raises Cancer Risk
Type 2 diabetes is for the majority of sufferers a self-inflicted problem. It is usually a consequence of becoming fat and sedentary: if you avoid both of those, then it is unlikely to happen to you. Even in the comparatively late stages type 2 diabetes can be reversed by nothing more than increasingly dramatic diet alterations and consequent loss of excess fat tissue. Here researchers show that the progressive dysfunction leading to diabetes is also raising cancer risk:
Prediabetes is a general term that refers to an intermediate stage between normoglycaemia and overt diabetes mellitus. It includes individuals with impaired glucose tolerance (IGT), impaired fasting glucose (IFG) or a combination of the two. Results to date from prospective cohort studies investigating the link between prediabetes and risk of cancer are controversial. Thus in this new study, the authors did a meta-analysis to evaluate the risk of cancer in association with the impaired fasting glucose and impaired glucose tolerance population.The researchers found that prediabetes was associated with a 15% increased risk of cancer overall. The results were consistent across cancer endpoint, age, duration of follow-up and ethnicity. There was no significant difference for the risk of cancer with different definitions of prediabetes (IGT or IFG). The authors note that it has been reported that obesity, an important risk factor for diabetes, is also linked to the development of cancer. For this reason, they performed a sensitivity analysis that only included studies that adjusted for BMI in the meta-analysis. They say: "We found that, after controlling for BMI, the presence of prediabetes remained associated with an increased risk of cancer of 22%."
The authors say several possible mechanisms could explain the results. First, chronic hyperglycaemia and its related conditions, such as chronic oxidative stress and the accumulation of advanced glycated endproducts (that are made in conditions of excessively high blood sugar) may act as carcinogenic factors. Second, increased insulin resistance leads to increased insulin secretion, which can in turn allow cancer cells to grow and divide. Third, there could be genetic mutations which predispose individuals to an increased risk of cancer, with one recent study showing that a malfunction in a tumour suppressor gene exposed individuals to increased risk of both cancer and prediabetes.
Link: http://www.sciencedaily.com/releases/2014/09/140908204706.htm