Pancreatic cancer and diabetes: Is there a relationship? A case-controlledstudy

Background: There is controversy about whether diabetes mellitus is a risk factor for pancreatic cancer or an epiphenomenon of the cancer. The present study aims to determine if long-term diabetes is a risk factor for pancrea tic cancer. Methods: The study undertook to determine the prevalence of diabetes among three matched (age/gender) patient groups (pancreatic cancer (PaC), colorec tal cancer (CRC), and fracture neck of femur (NOF)) at the date of diagnosi s of cancer or fracture as well as 1 and 5 years prior to this. A retrospec tive review of the medical records of the three groups of patients was unde rtaken. Patients identified with PaC in the period July 1994 to February 19 98 were age (+/- 5 years)- and gender-matched to patients identified in the same time period with NOF and with CRC. The data were then analysed using McNemar's test for discordant pairs. Results: Over a 44-month period 116 patients with PaC were identified of wh ich 24% had diabetes at the time of diagnosis of their malignancy (NOF, 8%; CRC, 9.5%). There was a statistically significant difference (PaC and NOF, P < 0.01; PaC and CRC, P < 0.01). For a duration of diabetes of > 5 years the prevalence of diabetes fell to 7.8% in the PaC group, to 6% in the NOF group and to 6.9% in the CRC group, with no significant difference between the groups. Conclusion: There is no increase in the prevalence of long-standing diabete s mellitus in patients with PaC compared to age- and gender-matched control s with NOF and CRC. The relationship of PaC and diabetes may be an epipheno menon, rather than diabetes being a risk factor for pancreatic malignancy.