The mitochondria are involved in active and dynamic processes, such as mitochondrial biogenesis, fission, fusion and mitophagy to maintain mitochondrial and cellular functions. In obesity and type 2 diabetes, impaired oxidation, reduced mitochondrial contents, lowered rates of oxidative phosphorylation and excessive reactive oxygen species (ROS) production have been reported. Mitochondrial biogenesis is regulated by various transcription factors such as peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), peroxisome proliferator-activated receptors (PPARs), estrogen-related receptors (ERRs), and nuclear respiratory factors (NRFs). Mitochondrial fusion is promoted by mitofusin 1 (MFN1), mitofusin 2 (MFN2) and optic atrophy 1 (OPA1), while fission is governed by the recruitment of dynamin-related protein 1 (DRP1) by adaptor proteins such as mitochondrial fission factor (MFF), mitochondrial dynamics proteins of 49 and 51 kDa (MiD49 and MiD51), and fission 1 (FIS1). Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) and PARKIN promote DRP1-dependent mitochondrial fission, and the outer mitochondrial adaptor MiD51 is required in DRP1 recruitment and PARKIN-dependent mitophagy. This review describes the molecular mechanism of mitochondrial dynamics, its abnormality in diabetes and obesity, and pharmaceuticals targeting mitochondrial biogenesis, fission, fusion and mitophagy.