Interstitial glucose in skeletal muscle of diabetic patients during an oral glucose tolerance test

Abstract

Aim The presence of a transcapillary arterial–interstitial gradient for glucose (AIG_glu) in skeletal muscle may be interpreted as a consequence of intact cellular glucose uptake. We hypothesized that the AIG_glu decreases in Type 2 diabetes mellitus as a consequence of insulin resistance, whereas it remains intact in Type 1 diabetes. Methods Glucose concentrations were measured in serum and interstitial space fluid of skeletal muscle during an oral glucose tolerance test (OGTT) in patients with Type 1 and Type 2 diabetes and in young and middle‐aged healthy volunteers, using microdialysis. Results The area under the curve for glucose in serum (AUC_SE) was higher than in interstitial space fluid of skeletal muscle (AUC_MU) in healthy young (AUC_SE = 1147 ± 332 vs. AUC_MU = 633 ± 257 mM/min/ml; P = 0.006), healthy middle‐aged volunteers (AUC_SE = 1406 ± 186 vs. AUC_MU = 1048 ± 229 mM/min/ml; P = 0.001) and in Type 1 diabetic patients (AUC_SE = 2273 ± 486 vs. AUC_MU = 1655 ± 178 mM/min/ml; P = 0.003). In contrast, in Type 2 diabetic patients AUC_SE (2908 ± 1023 mM/min/ml) was not significantly different from AUC_MU (2610 ± 722 mM/min/ml; P = NS). Conclusion The present data indicate that AIG_glu is compromised in Type 2 diabetes in contrast to Type 1 diabetes where it appears to be normal. Because no changes in muscle blood flow were detected, insulin resistance appears to be the main cause for the observed decreased AIG_glu in skeletal muscle in Type 2 diabetic patients.