Calcium and calcitonin responses to calcium infusion in type I diabetes mellitus

Coincident diabetes mellitus and primary hyperparathyroidism

The prevalence of diabetes mellitus in primary hyperparathyroidism is approximately 8% and that of primary hyperparathyroidism in diabetic patients is approximately 1%. Both values are about three-fold higher than the respective expected prevalences in general populations. Patients with both disorders are over 40 years of age and 80% are female; 22% have type 1 and 78% type 2 diabetes. Primary hyperparathyroidism presents first in approximately 20% of patients, and diabetes mellitus in 40%; both disorders present together, or within 1 year, in 40%. Approximately 40% of patients with primary hyperparathyroidism have impaired glucose tolerance. Insulin resistance is present in hyperparathyroidism and probably arises from a raised intracellular free calcium concentration which, by decreasing normal insulin-stimulated glucose transport, increases the requirement for insulin: if this insulin resistance progresses, impaired glucose tolerance and diabetes mellitus would result. Parathyroidectomy has been followed by regression of diabetes and of impaired glucose tolerance in some but not all patients. Early diagnosis of the second disorder is clinically desirable when one disorder is present. Hyperparathyroid patients should therefore be screened for impaired glucose tolerance and diabetes annually, and pre-operatively. Diabetic patients should be checked for hypercalcaemia at appropriate intervals; although only 1% of them may have hyperparathyroidism, this disorder if untreated is associated with hypertension, to which diabetic patients are already prone.

Senile diabetes and bone mineral density

Bone mineral density was determined in a series of 67 elderly diabetics (38 males and 29 females) and 40 non-diabetic elderly subjects (20 males and 20 females) at the third medial and tenth ultradistal of the non-dominating radius using an X-ray densitometer (DEXA). Bone metabolism markers (Ct, PTH, HOP, UCA, AP, Vit-25-OH-D, BGP) were also measured. Our results indicate that there is no significant difference in values of BMD and the bone metabolism markers studied between diabetic and non-diabetic elderly subjects. We believe that senile diabetes is not a risk factor of onset and maintenance of senile osteoporosis.

Bone densitometry and biochemical bone remodeling markers in type 1 diabetes mellitus

Bone mineral density (BMD) at the lumbar spine, quantified by dual energy X-ray absorptiometry, and biochemical bone remodeling markers (serum alkaline phosphatase, osteocalcin, tartrate-resistant acid phosphatase and urinary hydroxyproline) have been studied in 94 patients with diabetes mellitus aged 18-62 years. BMD was normal (1.13 +/- 0.02 g/cm2 in patients vs. 1.16 +/- 0.12 g/cm2 in controls), although it was found to be negatively correlated with HbA1, microalbuminuria, age and the duration of the disease. Serum alkaline phosphatase (188 +/- 75 I.U./l vs. 168 +/- 42 I.U./1; P < 0.03), serum tartrate-resistant acid phosphatase (14.3 +/- 4.3 I.U./l vs. 11.7 +/- 3.7 I.U./l; P < 0.0001) and urinary hydroxyproline (0.018 +/- 0.016 mmol/mmol creatinine vs. 0.011 +/- 0.008 mmol/mmol creatinine; P < 0.001) were higher in diabetics than in controls. Serum osteocalcin was lower (2.5 +/- 1.3 ng/ml vs. 3.4 +/- 1.2 ng/ml; P < 0.0001). No relationship was found between bone remodeling markers and BMD. It is concluded that lumbar BMD is normal in type 1 diabetic patients, although the degree of metabolic control, age and duration of the disease may affect it. In the light of the biochemical markers, bone remodeling may be disturbed in diabetes, but such disturbance seems to be unimportant regarding BMD.