Diabetes increases the risk of colorectal cancer in Puerto Rico

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Introduction: The purpose of this study was to determine the extent to which diabetes mellitus (DM) increases the risk of developing CC within a sample of the Puerto Rican population, and to establish whether this risk was greater in patients with public rather than private health insurance.Puerto Ricans are the ethnic group with the second highest prevalence of diabetes mellitus (DM) in the United States. Additionally, age-standardized incidence rates of colorectal cancer have been steadily increasing in Puerto Rico. Multiple studies have documented an association between DM and an increased risk of colon cancer (CC) which is consistent between men and women, type of study conducted (case-control vs. cohort studies), and nationality. However, the link between DM and CC has scarcely been studied among Hispanic populations and among patients with different types of health insurance. This study represents the first such analysis in Puerto Rico.
 Hypothesis: Based on these data we hypothesize that in the Puerto Rican population, diabetic patients have a higher risk of developing CC than non-diabetics, and that this risk is greater among patients with public rather than private health insurance.
 Methods: Our study is a cross-sectional analysis of health data submitted in Puerto Rico during the years 2000-2002 to a public and private health insurance companies. We analyzed the data in terms of the combined population, type of insurance coverage, and sex. Proportional odds ratios (PORs) and 95% confidence intervals (CIs) were used to characterize the risk of diabetic patients developing CC. CIs were calculated using the method by Woolf.
 Results: Together, these data sets encompass approximately 25% of all insured patients in Puerto Rico. In the combined patient population, diabetics had an increased risk of developing CC (POR = 5.06, 95% CI = 4.69-5.45). When stratifying the combined patient population by sex, diabetic females and males had an increased risk of developing CC (females: POR = 4.6, 95% CI = 4.47-5.50; males: POR = 5.17, 95% CI = 4.64-5.77). Diabetic patients with public health insurance (POR = 5.89, 95% CI = 5.36-6.49) had a greater risk of developing CC than diabetic patients with private health insurance (POR = 4.14, 95% CI = 3.66-4.68). Stratifying patients with public health insurance by sex, both diabetic females and males had an increased risk of developing CC (females: POR = 6.07, 95% CI = 5.34-6.89, males: POR = 4.50, 95% CI = 3.82-5.32). Stratifying patients with private health insurance by sex, both diabetic females and males had an increased risk of developing CC (females: POR = 3.75, 95% CI = 3.11-4.51; males = POR = 5.76, 95% CI = 4.98-6.66).
 Conclusions: Our data suggest that within the Puerto Rican population, diabetics have a very high risk of developing CC. Furthermore, this risk is greater among patients with public rather than private health insurance. These results will be further evaluated in a prospective cross-section study to assess causality.