Insulin resistance and not hyperinsulinaemia determines erythrocyte Na+/Li+ countertransport in non-insulin-dependent diabetes mellitus.
Insulin resistance and increased erythrocyte Na+/Li+ countertransport activity are well documented in subjects with essential hypertension, raising the question whether compensatory hyperinsulinaemia might be responsible for activating Na+/Li+ countertransport. We measured Na+/Li+ countertransport in 63 non-nephropathic non-insulin-dependent diabetic subjects (36 hypertensive, 27 normotensive), finding no correlation with fasting levels of insulin (r = 0.074, P = 0.28), despite using a sensitive and specific insulin assay. In contrast, in 33 of the subjects in whom insulin sensitivity was measured, Na+/Li+ countertransport correlated significantly with the whole body glucose clearance rate (r = -0.37, P = 0.036). It is concluded that increased Na+/Li+ countertransport may be a cellular marker for insulin resistance, but that hyperinsulinaemia is not likely to be the factor which mediates this relation.
University College London School of Medicine, Department of Medicine, Whittington Hospital, UK.
J H
JH
Pinkney
A E
AE
Denver
W J
WJ
Foyle
C
C
Foster
J S
JS
Yudkin
D000368:Aged; D017920:Antiporters / Q000032:analysis*; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D004797:Enzyme-Linked Immunosorbent Assay; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D006801:Humans; D006946:Hyperinsulinism / Q000378:metabolism; D006973:Hypertension / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D007333:Insulin Resistance; D017136:Ion Transport; D008094:Lithium / Q000097:blood; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood
D017920:Antiporters; C045885:sodium-lithium countertransporter; D008094:Lithium; D011188:Potassium