Table 1: Possible categories for T2DM initiations and causality.

Etiology	Possible Pathological Pathways	References
Genetic/epigenetic	DNA methylation Copy-number change Gene transcription Loss-of-function mutation	[3-8]
Molecular	Growth factor excretion Leptin Insulin Adipose-hypoxia Adipocyte-respiration Pituitary hormonal synthesis and secretion	[7-9]
Chemical	Toxic compounds Other drugs	[10]
Physiology	Old age Liver dysfunction Inflammation Obesity Insulin-resistance Sleep problems Energy homeostasis Hypothalamic circuit Immune-metabolic pathways	[7-9, 11-18]
Food	More energy foods Palatable food (processed foods) Free-accessed foods	[11-13]
Life-style Behavior	Sedentary occupation Exercise deficiency Long-term TV watching Alcoholic Substance-addictive	[4, 5, 11-16]