When the oxygen supply is insufficient, this oxidation reaction cannot be carried out normally, and the body will supply energy to the human body in the form of anaerobic glycolysis. Fermentation can also produce a small amount of energy, but the metabolite produced during metabolism is lactic acid.

Therefore, when the oxygen supply is insufficient, it can lead to the increase of lactic acid in human body.

The increase of lactic acid in the body is only the accumulation of metabolites, such as the result of people feeling sore after a lot of exercise or labor.

The human body has a powerful compensation mechanism to neutralize these lactic acids without causing serious problems.

If there is any reason for the continuous increase of lactic acid in the body, the consequence is that "metabolic acidosis" will eventually occur.

It seems that there is no specific "disease" that can cause the increase of lactic acid alone.

Hypoxia can lead to an increase in lactic acid, but hypoxia is not a disease.