The mineralocorticoid hormone, aldosterone, is known to play a role in sodi
um homeostasis. We serendipitously found, however, highly significant assoc
iation between sing le-nucleotide polymorphisms in the alosterone synthase
gene and plasma glucose levels in a large population of Chinese and Japanes
e origin, Two polymorphisms-one in the putative promoter (T-344C) and anoth
er resulting in a lysine/arginine substitution at amino acid 173, which are
in complete linkage disequilibrium in this population-were associated with
fasting plasma glucose levels (P = 0.000017) and those 60 (P = 0.017) and
120 (P = 0.0019) min after an oral glucose challenge. A C/T variant in intr
on 1, between these polymorphisms, was not associated with glucose levels.
Arg-173 and -344C homozygotes were most likely to be diabetic [odds ratio 2
.51; 95% confidence interval (C.I.) 1.39-3.92; P = 0.0015] and have impaire
d fasting glucose levels (odds ratio 3.53; 95% C.I. 2.02-5.5; P = 0.0000036
). These results suggest a new role for aldosterone in glucose homeostasis.