Impaired betacell function in the presence of reduced insulin sensitivity determines glucose tolerance status in acromegalic patients - Kasayama, S; Otsuki, M; Takagi, M; Saito, H; Sumitani, S; Kouhara, H; Koga, M; Saitoh, Y; Ohnishi, T; Arita, N (Clin Endocrinol (Oxf), 2000)