Background: Insulin resistance is associated with advanced and moderate chr
onic renal failure (CRF). However, insulin resistance in chronic glomerulon
ephritis (CGN) before onset of frank renal dysfunction is not fully evaluat
ed. We attempted to investigate the association of insulin resistance with
mild renal dysfunction and with abnormal calcium homeostasis. Patients and
methods: Eighteen young, lean non-diabetic male patients with biopsy-proven
CGN (age 30 +/- 7 years, body mass index 23.0 +/- 2.5 kg/m(2)) were enroll
ed. Insulin sensitivity was estimated by the glucose infusion rate (M value
) during euglycemic hyperinsulinemic clamping for 60 to 120 min. Calcium-re
lated parameters including intracellular calcium concentrations ([Ca2+](i))
in platelets were also measured. Renal function was normal or slightly imp
aired (serum creatinine, 1.0 +/- 0.2 mg/dl; glomerular filtration rate (GFR
), 68 to 131 ml/min/1.48 m(2)). We divided subjects into an insulin-sensiti
ve (IS) group (M value > 7.3 mg/kg/min, the overall mean) and an insulin-re
sistant (IR) group (M value < 7.3 mg/kg/min). Results: During a 75 g oral g
lucose tolerance test, the plasma glucose concentration at 120 min after gl
ucose loading and the immunoreactive insulin concentration at 60 min were s
ignificantly higher in the IR group. GFR was notably lower in the IR group
than in the IS group (p = 0.0003), and was significantly correlated with in
sulin sensitivity (p < 0.02, r = 0.58). The basal [Ca2+](i) was significant
ly higher in the IR than in the IS group (39 +/- 9 vs. 30 +/- 9 nM, p < 0.0
5). Conclusion: Mild renal dysfunction and elevated basal [Ca2+](i) are ass
ociated with insulin resistance in CGN.