Hypoglycemia in the Context of Post-Bariatric Clinical Follow-Up: Is There a Blind Spot in Research and Care?

Post-bariatric hypoglycemia (PBH) is classically defined as venous glucose levels < 54 mg/dL accompanied by sympathetic or neuroglycopenic symptoms, with resolution after glucose correction (Whipple's triad), occurring in a typical post-surgical context (1-3 years after surgery, 2-4 h postprandially), after exclusion of other causes. Since 2015, studies using continuous glucose monitoring (CGM) have revealed a more complex glycemic profile following metabolic bariatric surgery (MBS) characterised by CGM-detected asymptomatic and nocturnal low interstitial glucose values, frequently occurring during prolonged intermeal periods, along with increased 24-h glycemic variability. Provocative tests are limited by non-physiological stimuli or poor standardisation. Meanwhile, although diagnostic workups for alternative etiologies not related to diabetes are recommended, these conditions are exceedingly rare compared with real-world CGM-detected events. Evidence from cohorts of individuals with diabetes links CGM metrics, such as nocturnal and prolonged intermeal low glucose exposure and glycemic variability, to adverse outcomes, including cardiovascular mortality, stroke, arrhythmias, next-day cognitive slowing, retinopathy, microalbuminuria, and arterial stiffness. These findings may support the potential prognostic relevance of similar phenotypes following MBS. We argue for: (1) a critical revision of diagnostic criteria, including standardised interstitial thresholds, event definitions, and the role of symptoms; and (2) prospective CGM cohorts of post-MBS patients without diabetes adequately sized to assess clinically meaningful endpoints, such as cardiovascular, microvascular, and cognitive outcomes. CGM has uncovered a likely blind spot in PBH, particularly asymptomatic and nocturnal hypoglycemia. Recognising this spectrum and aligning definitions, diagnostics, and care may improve outcomes.