To address this question, CD1d null mice (CD1d−/−), which lack NKT cells but have a full complement of CD8+ T-cells, and littermate wild type controls (WT) on a pure C57BL/6J background were exposed to a high fat diet, and glucose intolerance, insulin resistance, dyslipidemia, inflammation, and obesity were assessed. This evidence concerns the gene CD1D and metabolic syndrome.