Insulin resistance is not caused by a single vitamin deficiency; it is a multi-factor metabolic process. However, certain micronutrient deficiencies may negatively influence metabolic function. Low vitamin D status, magnesium deficiency, and imbalances involving B vitamins (such as B12) have been associated with insulin sensitivity in some populations. The key point: association does not automatically mean direct causation. Supplementation is most meaningful when a deficiency is confirmed; random use is not a safe or cost-effective strategy. The best approach is lab-based assessment (vitamin D, B12, ferritin, magnesium, etc.), strengthening nutrition, and using targeted support under clinician or dietitian guidance when needed. Lifestyle remains the primary driver; micronutrients play a supportive role.