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Essential micronutrients and biguanides (metformin) synergistic and antagonistic interactions on neurocognitive outcomes in type two diabetes mellitus: a systematic review of preclinical and clinical evidence

Ninsiima HI, Ainamani HE, Ayebazibwe G, Matovu D, Eze ED

Frontiers in endocrinology, 2026

2 citations

Abstract

Background: Type 2 diabetes mellitus (T2DM) represents a systemic disease that extends beyond metabolic dysfunction to include accelerated neurocognitive decline driven by oxidative stress, inflammation, and insulin resistance. Emerging evidence suggests that essential micronutrients may interact synergistically or antagonistically with biguanides, particularly metformin, to influence neurocognitive function. This systematic review synthesized preclinical and clinical evidence on the interactions between essential micronutrients and biguanides (notably metformin) in modulating neurocognitive outcomes in T2DM.

Methods: Following PRISMA 2020 guidelines, we systematically searched PubMed, Web of Science, and Scopus for studies published between 2010 and 2025. After screening 226 records in Rayyan, 40 studies met the inclusion criteria. Both preclinical and clinical studies were analyzed descriptively to identify patterns of mechanistic and functional outcomes. Extracted data covered intervention types, doses, duration, biomarkers, and cognitive outcomes.

Results: Of the 40 studies, 27 (67.5%) were preclinical and 13 (32.5%) were clinical, spanning 14 countries. Most interventions involved vitamin D, zinc, magnesium, vitamin E, or polyphenols, either alone or combined with metformin. Synergistic effects were observed in 77.5% of studies, with significant improvements in fasting plasma glucose, HbA1c, insulin sensitivity, and oxidative balance. Key molecular pathways involved…

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