Background/Purpose: Tumor necrosis factor (TNF), a pathogenic inflammatory mediator in Rheumatoid Arthritis (RA), has been shown to play an essential role in the pathophysiology of insulin resistance. Studies have demonstrated the effects of TNF on glucose metabolism, the most important of which is the promising reduction in blood sugar levels. Consequently, TNF inhibitors (TNFi) should have a clinically important impact on glucose control and confer benefits to patients with Type 2 Diabetes Mellitus (DM). More research is needed to fully understand the impact of biologics on glucose control. The objective of this study was to examine the effect of initiating biologic therapy on hemoglobin A1c (HbA1c) among RA patients.

Methods: This retrospective cohort study included adult RA patients who were prescribed one or two disease-modifying antirheumatic drugs, had at least two recorded HbA1c measurements, and were initiated on biologic therapy. RA patients with DM were included if they had an HbA1c > 6.5% in the 6 months prior to initiation of biologics. Glucose control was defined as HbA1c < 7.0% at their last test result following the initiation of biologics. Medians (interquartile ranges) and numbers (percentages) are reported for descriptive statistics. Stratified by DM diagnosis, change in HbA1c is represented by Kaplan-Meier plots between TNFi and non-TNFi groups and the hazard ratios reported. 

Results: Among the 266 RA patients, median age in years was 61 (15) and 48 (18.1%) were males. Biologic therapy distribution was: 93 (35.6%) Adalimumab, 78 (29.9%) Etanercept, 19 (7.3%) Infliximab, and 71 (27.2%) non-TNFi. Sixty-two (60.2%) of non-DM patients and 116 (71.2%) of the DM group were obese, and 23 (14.1%) of DM were on insulin. The median change in HbA1c in the DM group was -0.3 (1.6) and non-DM 0.2 (1.0). Among the DM group, at 1 year, 13% reached glucose control with TNFi and 12% with non-TNFi; no difference was found over the observed time (HR= 0.94; 95% CI = 0.53, 1.67). In the non-DM group, at 1 year, 2% had a final uncontrolled glucose result with TNFi and 3% with non-TNFi; no statistically significant differences in HbA1c was observed over time (HR = 0.65; 95% CI = 0.21, 2.05).

Conclusion: No statistically significant difference in HbA1c levels or glucose control could be determined from initiating biologics in non DMARD-naïve RA patients with or without DM. Further large-scale, prospective studies on the impact of biologic therapy on non-articular outcomes are warranted to assess the need of preferentially starting these medications in the above-mentioned population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effect-of-biologics-on-the-hemoglobin-a1c-in-a-population-of-rheumatoid-arthritis-patients/