The Association between Dietary Insulin Index and Load with Gastric Cancer in Afghanistan

Background Insulin has a critical role in the pathogenesis of several cancers. We are aware of no study that examined the association between dietary insulin index (DII) and dietary insulin load (DIL) and gastric cancer. Objective This study aimed to investigate the relationship between dietary insulin index and DIL and odds of gastric cancer in Afghanistan. Methods In this hospital-based case-control study, we recruited 90 patients with newly-diagnosed gastric cancer and 180 healthy controls in Kabul, Afghanistan. Cases were chosen based on convenience-sampling method from the patients with pathologically confirmed gastric cancer aged between 20 and 75 years that had been referred to Jamhuriat Hospital, Kabul, Afghanistan. We applied a pre-tested food frequency questionnaire for dietary assessment of study participants. DIL and DII were calculated based on earlier publications. Multivariable logistic regression models were applied to examine the association between DII and DIL and gastric cancer. Results Mean BMI of study participants was 23.55 +/- 3.06 kg/m(2), of them 73% were males. After adjustment for potential confounders, participants in the top tertile of DII had 3.96 times greater odds for gastric cancer compared with those in the first tertile (95% CI: 1.23, 12.69; P-trend = 0.03). After adjustment for potential confounders, people in the highest tertile of DIL were 3.41 times more likely to have gastric cancer compared with those in the lowest tertile (95% CI: 1.28, 9.09; P-trend = 0.01). These associations remained significant even after further controlling for BMI, family history of cancer, H. pylori infection and salt intake. Conclusion A significant positive association was seen between dietary insulin index and insulin load and odds of gastric cancer in Afghan adults. Prospective cohort studies are required to confirm our findings.