Effect of hypocalcaemia on glucose tolerance, insulin release and free fatty acid levels in human subjects.

Eight patients with hypocalcaemia who presented with frank or latent tetany due to parathyroid insufficiency or nutritional osteomalacia were studied. Their serum calcium ranged from 6·85 to 7·7 mg/100 ml (mean 7·33±0·36 mg/100 ml). In six of them, serum calcium after treatment varied from 8·4 to 9·2 mg/100 ml. In ten healthy normal subjects the serum calcium levels were 9·0-10·2 mg/100 ml (9·50±0·47 mg/100 ml). The blood glucose levels during a 3 hr oral GTT were significantly elevated during hypocalcaemia and returned to normal levels after treatment. Serum insulin levels were low at 60 and 120 min after the administration of glucose in hypocalcaemia but returned to normal once the serum calcium levels were above 8·4 mg/100 ml. The FFA levels were high during the low calcium state and reached normal levels after treatment. The above studies suggest that an optimal level of serum calcium is essential for glucose-induced insulin release.