Authors : Kadiri Muhammed Lawal; A. A. Jigam

Volume/Issue : Volume 11 - 2026, Issue 4 - April

Google Scholar : https://tinyurl.com/48cf6zpt

Scribd : https://tinyurl.com/4kfvevs5

DOI : https://doi.org/10.38124/ijisrt/26apr2466

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Abstract : Background: Glucose tolerance is a key indicator of metabolic health, and micronutrients such as vitamins A and C are known to influence glucose metabolism. However, the synergistic effects of these two vitamins on postprandial glucose dynamics remain poorly characterised, particularly in African populations.  Objective: This study investigated the individual and combined effects of oral vitamin A (100,000 IU) and vitamin C (1,000 mg) supplementation on glucose tolerance in apparently healthy female volunteers.  Methods: Twenty (20) apparently healthy, non-diabetic, non-smoking female subjects were recruited from the Federal University of Technology, Minna community. A repeated-measures design was used across four phases: glucose alone (Phase 1/control), glucose + vitamin A (Phase 2), glucose + vitamin C (Phase 3), and glucose + vitamins A and C (Phase 4). Each subject received 75 g of oral glucose dissolved in 200 mL of water, and fingertip capillary blood glucose was measured at 0 (fasting), 30, 60, 90, 120, and 150 minutes using a calibrated glucometer. Data were analysed using one-way ANOVA with TukeyKramer post hoc test and expressed as Mean ± SEM (n = 20). Significance was set at p ≤ 0.05.  Results: Fasting blood glucose levels did not differ significantly across all four phases (p > 0.05). In all phases, blood glucose rose significantly from baseline at 30 minutes, peaking between 30–60 minutes, then declining progressively toward 150 minutes. Phase 2 (glucose + vitamin A) produced the highest glucose surge at 30 minutes (104.80 ± 3.44 mg/dL) compared to the control (93.30 ± 4.43 mg/dL). Phases 3 and 4 showed glucose curves closely paralleling the control. Phase 4 subjects showed a secondary rise at 120 minutes (102.00 ± 2.38 mg/dL), though glucose declined significantly by 150 minutes.  Conclusion: Vitamin A supplementation transiently amplifies early postprandial glucose elevation, possibly through enhanced pancreatic beta-cell insulin signalling. Vitamin C supplementation did not significantly alter glucose tolerance profiles. The combined supplementation of vitamins A and C demonstrated a delayed secondary glucose rise, suggesting a potential modulatory effect on glucose absorption and disposal. These findings support the potential role of vitamin supplementation as an adjunct strategy in glycaemic management.

Keywords : Glucose Tolerance; Oral Glucose Tolerance Test (OGTT); Vitamin A; Vitamin C; Postprandial Glycaemia; Diabetes Mellitus; Micronutrient Supplementation.

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