Effects of Excessive Ingestion of Sodium and Potassium Salts on Carbohydrate Metabolism and Blood Pressure in Diabetic Children

Abstract

The effects of ingesting excessive quantities of sodium and potassium salts on the blood pressure and carbohydrate metabolism have been studied in one non-diabetic and four diabetic children. Repeated tests were made in the case of each diabetic subject. While the most striking effects were observed in the case of one particular diabetic, who consistently required between 60 and 90 gm. of NaCl daily to satisfy his craving for salt, all patients submitted to the tests responded in like manner. The daily ingestion of between 1 and 2 gm. of NaCl per kilogram of body weight resulted within a period of from 2 to 4 days in a gain of from 4 to 5 per cent in body weight and an increase in both systolic and diastolic blood pressure to new plateaus between 30 and 50 per cent above the control levels. These higher pressures were maintained so long as the salt was taken. In addition to this effect on blood pressure, the excessive ingestion of NaCl was found to cause a marked reduction in the degree of glycosuria in the diabetic subjects studied. The effects were qualitatively the same in one mildly diabetic patient not given insulin as in those patients who received insulin at regular 6-hour intervals. The fasting blood sugar was found to range at lower levels after a few days of the high NaCl ingestion than during the foreperiod, the patient's food intake, insulin dosage and activity remaining unchanged. The fasting R.Q. was slightly higher during the period of high NaCl intake than previously. The shape of the sugar tolerance curve, however, was not measurably influenced by salt ingestion. In severe diabetes, ketonuria appeared earlier after withdrawal of insulin when the NaCl intake was low than when it was very high. With a constant protein intake estimated to maintain nitrogen balance under ordinary conditions the nitrogen output exceeded the intake during periods of low NaCl intake. During periods of high NaCl intake, however, the nitrogen balance became positive. Typical insulin reactions were found to occur at times during the period of high NaCl intake in patients receiving insulin in dosages found during the low-salt periods to be sufficient to completely prevent glycosuria. Sodium bicarbonate and sodium citrate when given in amounts with equivalent sodium values had similar though less marked effects than those of NaCl. The maximum effects of NaCl on both the B.P. and the carbohydrate metabolism were obtained only when the patients were given simplified diets which were low in potassium. Ordinary diets, high in potassium, either prevented or greatly lessened the effects of the NaCl. Potassium chloride, when given in doses of 10 to 20 gm. daily along with a simplified diet low in sodium, resulted in a slight fall in both systolic and diastolic blood pressure and at the same time a significant increase in the degree of glycosuria, thus exerting effects diametrically opposite those of the sodium salt. When the two salts were given simultaneously one part of potassium was found to completely abolish the effects of at least three chemically equivalent parts of sodium. A small number of serum potassium determinations have been made. The high NaCl intake depresses the serum potassium.