The respiratory quotient in diabetes

Oxidation of protein in the body really consists in the destruction of a great variety of amino-acids. When glucose arises from protein in diabetes the oxidation is different from the normal. When the D : N ratio is 3.65 the respiratory quotient for protein falls from 0.801 to 0.634. From Osborne's analyses of meat protein, recalculated on the basis of Osborne's own determination of the deficiency of the analytical methods employed, it may be calculated that the six sugar-forming amino-acids, glycocoll, alanine, aspartic acid, glutamic acid, proline and arginine, are present to the amount of 64.5 grams in 100 grams of meat protein. From the work of Ringer and Lusk and of Dakin and Dudley, it may be estimated that 44.4 grams of glucose arise from the several quantities of these amino-acids contained in 100 grams of meat. This would indicate a D : N of 2.75 and would explain the origin of 76 per cent. of the maximal sugar production from protein.

The estimated quantity of 64.5 grams of sugar-forming amino-acids would yield a respiratory quotient of 0.915 when oxidized normally, but if 44.4 grams of glucose be produced from them the respiratory quotient sinks to 0.675.

If one subtracts the influence of these sugar-forming amino-acids and the influence of the 1.07 grams of protein ammonia from the normal respiratory exchange, one may calculate that the respiratory quotient which represents the oxidation of the non-sugar-forming amino-acids is 0.716.

If one turns to Osborne's analyses it is found that the nonsugar-forming amino-acids consist in larger part (20 grams) of leucine, lysine and valine with respiratory quotients of 0.73, 0.71, 0.75 and in lesser quantity (7 grams) of histidine, phenylalanine and tyrosine with quotients of 0.90, 0.87, 0.89.