Phosphate is an active participant in energy metabolism, and its deficiency has been
associated with changes in insulin sensitivity and glucose tolerance. In the present
study, we have investigated insulin secretion and glucose tolerance in individuals
with moderate and acute phosphate deprivation and in patients with chronic hypophosphatemia.
The individuals with dietary phosphate deprivation, evidenced by a significant reduction
in phosphaturia from 232.3 ± 37.1 to 56.8 ± 23.9 mmol/24 hours, but with normal serum
levels of inorganic phosphorus, presented circulating glucose and insulin levels similar
to those of the pre-dietary period during the oral and intravenous glucose tolerance
tests. In contrast, patients with chronic hypophosphatemia (inorganic phosphorus <
0.65 mmol/l) presented in hyperinsulinemia during the postabsorptive state and during
the early and late phases of insulin secretion after the oral and intravenous glucose
stimulus. The physiological response of a fall in serum phosphate after glucose administration
observed in individuals with chronic hypophosphatemia was similar to that of normal
individuals. The presence of hyperinsulinemia both basally and after glucose stimulation,
with normal glycemia, in phosphate-depleted individuals suggests that this condition
is associated with reduced insulin sensitivity. However, severe phosphate deprivation
is necessary for the manifestation of this undesirable association. The deviation
of phosphate to the intracellular medium occurring after glucose administration in
hypophosphatemic individuals is similar to that of normal individuals and explains
the occurrence of severe hypophosphatemia in malnourished hypophosphatemic individuals
when submitted to parenteral refeeding.
Key words
Insulin Sensitivity - Mineral Metabolism - Hypophosphatemia - β-Cell Responsiveness
