Investigating the risk of Incident diabetes mellitus among primary care patients treated with simvastatin in North-Central Trinidad

AIM: To determine the risk of new-onset diabetes mellitus in patients treated with simvastatin at primary healthcare clinics in North Central Trinidad. MATERIALS AND METHODS: A retrospective descriptive case-series study design was applied to 384 conveniently sampled patient medical records from the cluster of primary healthcare centers during the period of February 2016–May 2016. Information from the patient files were then recorded using a systematic data extraction form. The major inclusion criteria were non-diabetic patients who were compliant with daily simvastatin for a minimum period of 1 year. The risk of incident diabetes mellitus was calculated, using SPSS version 20.0. Chi-squared (χ(2)) testing was performed to determine any association between new-onset diabetes mellitus and simvastatin use. RESULTS: In all, 207 patients became diabetic during their treatment period translating into a 53.9% risk of incident diabetes mellitus (χ(2) = 2.3438, P = 0.1258). A subgroup analysis of 133 subjects was performed to eliminate the confounders of family history of diabetes and age greater than 60 years. In this subgroup, 50 incident diabetics (37%) were identified and a statistically significant association was observed (χ(2) = 8.118, P = 0.0042). Linear regression revealed that this association was dose-dependent with a corresponding 32% higher risk in patients taking 40 mg (P = 0.001) of simvastatin daily compared with 20 mg of simvastatin (P = 0.094). Linear regression also revealed that there was significant statistical association between onset of diabetes mellitus and duration of statin therapy (P = 0.006). CONCLUSION: In this population, simvastatin use is associated with a 53.9% increased risk of development of new-onset diabetes mellitus (χ(2) = 2.3438, P = 0.1258). A statistically significant association was attained after subgroup analysis involving patients less than 60 years old and without a family history of diabetes with an incident risk of 37%. The increased risk of incident diabetes mellitus conferred by higher doses of simvastatin warrants consideration by physicians considering therapies for dyslipidemia in patients with multiple risk factors for diabetes mellitus.