Low dose allopurinol is associated with modest but significant improvements in glycemic control (GC) and glycemic variability (GV) in patients with type 2 diabetes mellitus: A cross-sectional study

Background: Type 2 diabetes mellitus (DM), gout, and asymptomatic hyperuricemia are inter-connected pathologies. Glycemic control (GC), involving a range of treatments is central to the management of DM, whereas allopurinol continues to be the most widely recommended urate lowering agent. Allopurinol has been shown to possess anti-oxidant properties: this study explores the favorable potential effect of allopurinol on glucose homeostasis. Methods: This is an observational study with a cross-sectional design performed on patients with type 2 diabetes mellitus (DM), recruited from centers in Saudi Arabia. Patients were divided into two groups; allopurinol users; (for gout or asymptomatic hyperuricemia) and matching control patients. Patient demographics, co-morbid conditions, biochemical tests, and pharmacological treatments were extracted from electronic records to investigate the effect of allopurinol therapy on Glycemic control (GC), as assessed by glycated haemoglobin (HbA1c as primary endpoint), and on parameters of glycaemic variability (GV) (secondary endpoints). Results: A total of 194 patients with type 2 DM were recruited (97 in both groups). The two groups were matched for age and sex: mean age: 59.4 years, 73% males in the allopurinol group vs 59.6 years, 73% males in the control group. Allopurinol, daily dose 100 mg, was prescribed for 77% of the patients, with median duration of 39.5 months treatment. HbA1c values were; 6.90% (6.20, 7.80) in the allopurinol group vs 7.30% (6.60, 8.40) in the control group (P=0.010). Parameters of GV were calculated from 3 consecutive fasting blood sugar (FBS) readings: variability independent of the mean (VIM) was 0.140 in the allopurinol group vs 0.987 in the control group (P<0.001). Conclusion: Concomitant low-dose allopurinol therapy in patients with type 2 DM was associated with modest but significant improvements in GC and GV.