Dopamine 2 Agonists for the Management of Type 2 Diabetes: a Systematic Review and Meta-analysis

Background: The Dopamine-2 receptor agonists, Bromocriptine and Cabergoline, were originally introduced for prolactinomas, pituitary tumors, and parkinson's disease but have glucose-lowering effects. This paper systematically reviewed the significance of their effects on lowering blood glucose level and conducted a comprehensive systematic search to identify relevant clinical trials of dopamine 2 agonists on glycated hemoglobin (HbA1c) and fasting blood sugar (FBS).

Method: We conducted a systematic review search in the databases (PubMed, Google Scholar, Cochrane Library, Registers, and Citations) until November 30, 2022, using the PRISMA 2020 statement. The Oxford quality score (Jadad score) was used to assess the study's quality. The present study protocol was registered on the PROSPERO database with ID: CRD42023389582. The study included studies with full abstracts, predefined doses, clear interventions, and blood glucose measurements.

Result: Data were synthesized from 23 clinical studies that recruited 6125 study subjects. The pooled effect analysis of the clinical trials revealed that dopamine 2 agonists improved HbA1c [SMD = -1.26; 95% CI (-1.60, -0.93),  < .00001], and FBS [SMD = -1.84; 95% CI (-2.61, -1.07),  < .00001]. Each drug's pooled effect analysis indicates bromocriptine significantly improved HbA1c [SMD = -1.25; 95% CI (-1.64, -0.87),  < .00001] and FBS [SMD = -1.90; 95% CI (-2.79, -1.01),  < .00001] and similarly, cabergoline significantly improved HbA1c [SMD = -1.29; 95% CI (-1.96, -0.62),  < .00001] and FBS [SMD = -1.62; 95% CI (-2.82, -0.41),  < .00001]. The pooled and individual analyses demonstrated that dopamine 2 agonists have a significant ability to lower blood glucose levels in clinical studies.

Conclusion: This study shows that dopamine 2 agonists significantly lowered FBS and HbA1c levels without causing severe negative effects. Even though the results are promising, additional research is necessary to establish the appropriate antihyperglycemic dosage, frequency of daily use, side effects, and potential product interactions when employing dopamine 2 receptor agonists for their antihyperglycemic effect.