Pre-existing diabetes mellitus in patients with multiple myeloma

Objectives: Type 2 diabetes mellitus is present in approximately 10% of patients at diagnosis of multiple myeloma (MM) and is associated with increased risks of adverse events caused by novel antimyeloma agents. However, the impact of type 2 diabetes on the survival of patients with MM has not been studied. Methods: We enrolled newly diagnosed patients with MM in Taipei Veterans General Hospital between 1999 and 2007 and identified those with pre-existing diabetes. The impact of pre-existing diabetes on patients with MM was evaluated by comparing clinical features, treatments and adverse reactions related to glycaemic control and overall survival (OS) of patients with and without pre-existing diabetes. Results: Of 310 patients with MM, 73% were men and 40 (12.9%) had pre-existing diabetes. Compared with their non-diabetic counterparts, MM patients with pre-existing diabetes had a significantly higher proportion of renal impairment [(RI), serum creatinine ≥2.0 mg/dL] and International Staging System stage III at diagnosis, and a significantly lower proportion of bisphosphonate use and a lower rate of RI reversal (P = 0.087). During the course of the disease, hyperglycaemia and hypoglycaemia of any grade were noted in 23 (67.6%) and 6 (17.6%) of these patients, respectively. Antidiabetic therapy was changed in 10 (29.4%) of 34 evaluable patients. MM patients with pre-existing diabetes had a significantly higher all-cause mortality risk (hazard ratio, 1.509; 95% confidence interval, 1.023-2.225, P = 0.037) compared with their non-diabetic counterparts. Conclusions: Our study demonstrated the impact of pre-existing diabetes on clinical features and OS in patients with MM.