Mineral deficiencies can cause impaired insulin release and insulin resistance. This study was conducted to investigate the relationship between hair mineral concentrations and insulin resistance in patients with metabolic syndrome (MS). A total of 456 subjects (161 patients with MS and 295 subjects without MS) were reviewed, and fasting plasma glucose, triglycerides, HDL-cholesterol, homeostasis assessment model-insulin resistance (HOMA-IR), and hair mineral concentrations were analyzed. While hair sodium and potassium concentrations were significantly higher, the hair calcium, magnesium, and zinc concentrations were lower in the MS group than in the control group. Regarding toxic element measurements, the hair arsenic (As) and lead (Pb) concentrations were higher in the MS group than in the control group. The results of multiple regression analysis, after adjusting for age, showed significant relationships between the Na/Mg and Ca/P ratios and HOMA-IR (R (2) = 0.109, p < 0.05). The Ca, Na, K, and B concentrations were also associated with HOMA-IR (R (2) = 0.116, p < 0.05). The hair Na concentration was significantly associated with MS, even after adjusting for age, visceral adipose tissue, and HOMA-IR (OR 1.020; 95 % CI 1.001-1.040; p = 0.036). Our findings suggest that hair mineral concentrations, such as calcium, magnesium, zinc, sodium, and potassium concentrations, may play a role in the development of insulin resistance.