Sodium-lithium countertransport activity and insulin resistance in normotensive IDDM patients.
In insulin-dependent diabetes (IDDM), an overactivity of sodium-lithium countertransport (Na+/Li+ CT) has been associated with the risk of nephropathy and hypertension, two conditions of insulin resistance. We investigated the sensitivity to insulin with a hyperinsulinemic (approximately 719 pM [approximately 100 microU/ml]) euglycemic clamp in two groups of normotensive nonproteinuric IDDM patients; 12 (10 men, 2 women) had high Na+/Li+ CT activity (mean 0.47, range 0.42-0.68 mmol/L red blood cells [RBC]/h, group 1) and 12 (9 men, 3 women) had normal Na+/Li+ CT activity (mean 0.24, range 0.12-0.31 mmol/L RBC/h, group 2). The two groups were similar in age (mean +/- SE 36 +/- 2 vs. 33 +/- 1 yr), duration of diabetes (19 +/- 3 vs. 18 +/- 2 yr), body mass index (26 +/- 0.8 vs. 24 +/- 0.6 kg/m2), arterial blood pressure (systolic/diastolic 121 +/- 4/79 +/- 2 vs. 122 +/- 3/77 +/- 2 mmHg), and glycemic control (HbA1 8.5 +/- 0.4 vs. 8.0 +/- 0.4%). Albumin excretion rate (AER) ranged between 4.7 and 148 (geometric mean 14) micrograms/min in group 1 and between 2.7 and 93 (geometric mean 11) micrograms/min in group 2. There were four microalbuminuric patients (AER greater than 30 micrograms/min) in each group. Whole-body glucose uptake was significantly reduced on average in group 1 compared with group 2 (41.6 +/- 2.2 mumol.kg-1.min-1 [7.48 +/- 0.4 mg.kg-1.min-1] vs. 49.6 +/- 2.2 mumol.kg-1.min-1 [8.93 +/- 0.4 mg.kg-1.min-1, P = 0.03), but some overlap existed between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Lopes de Faria
J B
JB
Unit for Metabolic Medicine, United Medical School, Guy's Hospital, London, United Kingdom.
Jones
S L
SL
Macdonald
F
F
Chambers
J
J
Mattock
M B
MB
Viberti
G
G
D000328:Adult; D017920:Antiporters; D001059:Apoproteins / Q000097:blood; D001794:Blood Pressure / Q000502:physiology; D006332:Cardiomegaly / Q000453:epidemiology; D002352:Carrier Proteins / Q000502:physiology*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism / Q000503:physiopathology*; D004452:Echocardiography; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D015994:Incidence; D007333:Insulin Resistance / Q000502:physiology*; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D011507:Proteinuria / Q000453:epidemiology; D014280:Triglycerides / Q000097:blood; D014316:Tritium
D017920:Antiporters; D001059:Apoproteins; D002352:Carrier Proteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides; C045885:sodium-lithium countertransporter; D014316:Tritium; D005947:Glucose