Effects of Statin Therapy on Glycemic Control and Associated Factors Among Type 2 Diabetes Mellitus Patients in Northeastern Tanzania: A Retrospective Cohort Study

Introduction: Statins have been implicated in poor glycemic control among patients with diabetes mellitus (DM), prompting the US Food and Drug Administration (FDA) to update warning labels on all statins to reflect the risk of increased blood glucose levels. However, few studies from sub-Saharan Africa have assessed this concern. This study investigated the effects of statins on glycemic control among patients with Type 2 diabetes mellitus (T2DM) in Kilimanjaro, northeastern Tanzania. Materials and Methods: This was a hospital-based retrospective cohort study evaluating changes in glycated hemoglobin (HbA1c) at 1-3, 7-12, and 19-24 months, as the primary outcome, comparing statin users and nonusers among T2DM patients attending DM clinic at Kilimanjaro Christian Medical Centre in Tanzania. Binomial regression models were fitted to calculate adjusted risk ratios for independent predictors of a ≥ 0.2% rise in HbA1c, with statistical significance set at p < 0.05. Results: Out of 122 patients, 51 (41.8%) were on statin therapy. Among these, 46 (90.2%) were prescribed atorvastatin. Statin users had an increase of mean HbA1c from 10.6% ± 2.7% at baseline compared to 11.6% ± 2.8% at 1-3 months (p = 0.114), followed by a decrease to 10.1% ± 2.2% at 7-12 months (p = 1.0), and 10.0% ± 2.5% at 19-24 months (p = 1.0). However, atorvastatin users (n = 46) had a significant increase of mean HbA1c from 10.7% ± 2.8% at baseline compared to 11.9% ± 2.7% at 1-3 months (p = 0.04). In contrast, nonstatin users had a consistent and significant decrease in HbA1c from 11.3% ± 2.8% at baseline compared to 9.7% ± 2.2% at 1-3 months (p = 0.001), to 9.7% ± 2.6% at 7-12 months (p = 0.011), and to 9.3% ± 2.2% at 19-24 months (p = 0.001). Conclusion: Statin therapy among patients with T2DM was associated with short-lived worsening of glycemic control at 1-3 months posttherapy.