ABSTRACT Objective Metabolic and bariatric surgery has a definite role in the management of obese patients with type 2 diabetes mellitus (T2DM). There is also evidence of such surgery improving the health of type 1 diabetic (T1DM) patients. The aim of this paper is to explore the effect of metabolic and bariatric surgery on T1DM. Materials and methods A comprehensive search of PubMed and Google Scholar was performed to identify relevant papers reporting metabolic and bariatric surgery effects on T1DM. A statistical analysis is applied after data synthesis. A forest plot and Pearson correlation are then calculated. Results Of the 567 papers that were identified, 558 articles did not fulfill the inclusion criteria and were therefore excluded. Nine studies involving 78 patients were selected for this metaanalysis. There was improvement in HBA1c (p value = 0.40), insulin dose (p value = 0.0001) and BMI (p value = 0.00001) after surgery. However, improvement in the HBA1c did not reach statistical significance. There was a weak correlation between postoperative insulin dose and BMI change after surgery (r = -0.177). There was a negligible correlation between HBA1c and BMI change after operations (r = -0.01). Conclusion Current metabolic/bariatric surgery is improving T1DM in obese and morbidly obese patients. This is not exclusively related to excess weight loss (EWL) as previously thought. Therefore, there is a role for other factors, which are potential players to reproduce the same effect in nonobese T1DM patients.