An eight year old girl was just diagnosed with type 1 diabetes, and one test the doctors did was of her blood pH level. They said her level was decreased (about 7.23). Can you tell me why her blood pH level was decreased?

Briefly and simply, insulin governs the entry of glucose into the cell, and glucose is the principal fuel for the body as a whole. When there an insufficient supply of insulin as can be the case in type 1, the body breaks down fat as an alternative source of energy. This breakdown is incomplete though because ultimately it depends on normal glucose metabolism. As a result, there is an accumulation of ‘ketoacids’ such as acetoacetic acid. These acids in turn build up, as any acid will, and there is accumulation of hydrogen ions. Since pH is an expression of the reciprocal of the logarithm of the concentration of hydrions, there may be a fall in pH (In this case, from the normal level of 7.40 in the blood to 7.23, a significant change).

In the severe form of this, which is called DKA [diabetic ketoacidosis], it is considered best not to counter this with alkalis like bicarbonate, but to let the kidneys achieve homeostasis by giving adequate fluids.

This is an oversimplification, but any biochemistry textbook will explain this in more detail.

DOB