Let (X , d, μ) be a metric measure space satisfying the so-called upper doubling condition and the geometrically doubling condition. Let T be a Calderón-Zygmund operator with kernel satisfying only the size condition and some Hörmander-type condition, and b ∈ RBMO(μ) (the regularized BMO space with the discrete coefficient). In this paper, the authors establish the boundedness of the commutator T b := bT − T b generated by T and b from the atomic Hardy space H 1 (μ) with the discrete coefficient into the weak Lebesgue space L 1, ∞ (μ). From this and an interpolation theorem for sublinear operators which is also proved in this paper, the authors further show that the commutator T b is bounded on L p (μ) for all p ∈ (1, ∞). Moreover, the boundedness of the commutator generated by the generalized fractional integral T α (α ∈ (0, 1)) and the RBMO(μ) function from H 1 (μ) into L 1/(1−α), ∞ (μ) is also presented.