Acute biochemical variations induced by calcium citrate and calcium carbonate in type 2 diabetic patients - Impaired calcium absorption in type 2 diabetic patients with prolonged gastric emptying time

Calcium supplementation is important in the treatment of osteoporosis, a di sease that may also occur in diabetic patients. The acute effects of calciu m supplementation and their relationship to gastric emptying time, however, have rarely been studied in type 2 diabetic patients. We evaluated the acu te biochemical variations induced by the administration of two different ca lcium preparations, calcium citrate and calcium carbonate, in 16 (male/fema le: 13/3) Chinese diabetic patients. Serum free calcium, intact parathyroid hormone (i-PTH), and amount of urinary excretion of calcium (uCal/uCr) wer e evaluated after a single dose of 1200 mg of elemental calcium in each pre paration. The free calcium levels did not change significantly in either gr oup. However, significant suppression of i-PTH after calcium citrate admini stration at 1 h (17.1 +/-2.0 pg/ml, P=.023), and after calcium carbonate: a dministration at 2 h (14.2 +/-2.5 pg/ml, P=.000), was noted when compared w ith individual basal level (21.2 +/-2.5 and 19.3 +/-2.4 pg/ml, respectively ). The suppressive effect on i-PTH lasted for 6 h after calcium citrate and 5 h after calcium carbonate preparation of the 6-h study period. After adm inistration of calcium citrate, the uCal/uCr of 2-to-4-h collection was sig nificantly higher than that of the basal and 0-to-2-h collections: 0.25 +/- 0.04 vs. 0.19 +/-0.03, P=.025; and 0.25 +/-0.04 vs. 0.19 +/-0.02, P=.014, r espectively. A similar finding was observed for calcium carbonate: 0.23 +/- 0.03 vs. 0.18 +/-0.02, P=.019; and 0.23 +/-0.03 vs. 0.18 +/-0.02, P=.011, r espectively. We conclude that, in this group of Chinese type 2 diabetic pat ients in our study, the oral administration of 1200 mf; elemental calcium i n either calcium citrate or calcium carbonate preparation can induce a sign ificant suppression of i-PTH. This may be helpful in preventing or treating osteoporosis. A prolonged gastric emptying time in these diabetic subjects may contribute to the non-significant alteration in free calcium levels af ter the administration of either calcium preparation. (C) 2001 Elsevier Sci ence Inc. All rights reserved.