Ca2+-Mg2+-ATPase activity and ionized calcium in Type 2 diabetic patients with neuropathy

Ca2+-Mg2+-ATPase is an important regulator of intracellular calcium concent ration and therefore, of erythrocyte deformability. We have investigated th e possible relationship between Ca2+-Mg2+-ATPase activity (ATPase) and ioni zed calcium (Ca2+), in diabetic patients with peripheral neuropathy. A tota l of 104 Type 2 diabetic patients (57 neuropathic and 47 non-neuropathic) a nd 25 non-diabetic subjects were studied. After an overnight fast, blood wa s taken for Ca2+-Mg2+-ATPase activity, Ca2+, Mg2+, PTH and HbA(1c). The neu ropathy study group had significantly lower levels of ATPase, 6.6; (95% CI, 5.6 7.7) mnol/mg/min compared to controls 7.1 (6.2-8.3) nmol/mg/min, P < 0 .001 and to diabetic patients without neuropathy 7.0 (6.0-8.1) nmol/mg/min, P < 0.001. The study group had also lower levels of Ca2+ (0.89+/-0.18 mmol /l vs, control 1.08+/-0.24 mmol/l, P<0.01 and non-neuropathic 0.98 +/- 0.27 mmol/l, P < 0.05) and Mg2+ (0.73 +/- 0.13 mmol/l vs, control 0.81 +/- 0.14 mmol/l, P < 0.05), despite similar PTH levels. In diabetic subjects, no co rrelation was found between ATPase or Ca2+ with glucose, HbA(1c), age or du ration of diabetes. We conclude that in patients with diabetic neuropathy t here are abnormalities of Ca2+-Mg2+ ATPase activity and Ca2+. This provides Further support for the rule of microangiopathy in the pathogenesis of neu ropathy. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.