Lavandula angustifolia (Lavender) has been studied on pharmacological properties such as anti-inflammatory, antioxidative, pain-reducing effects. Nicotine (NT), the main component of tobacco, and uncontrolled high glucose (HG) conditions in diabetic patients could affect dysregulation of intracellular Ca2+ as well as metabolic dysfunction. Therefore, we investigated to compare intracellular Ca2+ level in neurons, astrocytes, and microglia following glucose dysregulation in combination with (or without) a nicotine stimulus and to investigate the effects of lavender on this process. Treatment with NT plus HG significantly increased intracellular Ca2+ in neurons and microglia but not in astrocytes. Intracellular Ca2+ elevation was significantly reduced in the NT plus HG-pretreated cells mixed with neurons, astrocytes and microglia, with a two-fold increase in the applied number of astrocytes. Lavender significantly reduced NT plus HG-induced intracellular Ca2+ elevation in neurons and microglia, which was partially inhibited by the L-type Ca2+ channel inhibitor nifedipine and the T-type Ca2+ channel inhibitor mibefradil in neurons only but not in microglia. Lavender may be useful in protecting neurons by reducing elevated intracellular Ca2+ that is induced by NT plus HG via inhibition of L- and T-type Ca2+ channels. Astrocytes may protect neurons and microglia by reducing intracellular Ca2+ elevation via Ca2+ influx under the conditions of nicotine expose and glucose dysregulation. This work was supported by grants from the NRF-2021R1A2C2004118, Korea University, and Korea University Nursing Research Institute. *E-mail for corresponding author: ghseol@korea.ac.kr