ISSN:
1432-0428
Keywords:
Sodium-lithium countertransport activity
;
Type 1 (insulin-dependent) diabetes mellitus
;
insulin-mediated glucose disposal
;
albuminuria
;
hyperlipidaemia
;
hypertension
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Insulin resistance in Type 1 (insulin-dependent) diabetes mellitus may be associated with raised erythrocyte sodium-lithium countertransport activity in patients with hypertension, or nephropathy, or both. However, in these circumstances it is difficult to separate the impact of hypertension, hyperlipidaemia and nephropathy on erythrocyte sodium-lithium countertransport from that of insulin resistance. We have therefore examined the relationship between insulin-mediated glucose disposal and erythrocyte sodiumlithium countertransport in 41 normotensive (mean blood pressure 120/74 mm Hg), normoalbuminuric (mean albumin excretion 6.2 μg/min), normolipidaemic (mean serum cholesterol 4.3 mmol/l and mean serum triglycerides 1.0 mmol/l) Type 1 diabetic patients. Erythrocyte sodium-lithium countertransport was on average 0.31 mmol Li · h−1 · l erythrocytes −1 (range 0.07–0.69). Nine patients had values above 0.40 mmol Li · h−1 erythrocytes−1 (0.51±0.10 mmol Li · h−1 · l erythrocytes−1). The patients with high erythrocyte sodium-lithium countertransport were matched for age, sex, BMI, HbA1 and duration of diabetes, with nine patients with normal erythrocyte sodium-lithium countertransport. Insulin-mediated glucose disposal was evaluated during the last hour of a euglycaemic clamp (insulin 0.015 U · kg−1 · h−1; blood glucose clamped at 7.0 mmol/l). The free insulin levels were comparable between the patients with high and normal erythrocyte sodium-lithium countertransport (37.2±14.7 mU/l and 34.7±17.2 mU/l respectively). Insulin-mediated glucose disposal was on average 3.1±1.5 (range 0.8–6.8) mg · kg−1 · min−1. Erythrocyte sodium-lithium countertransport did not correlate with insulin-mediated glucose disposal in all 41 cases (r s=−0.14), but when the matched groups were compared, patients with raised erythrocyte sodium-lithium countertransport had lower insulin-mediated glucose disposal rates compared to those with normal erythrocyte sodium-lithium countertransport (2.7±1.1 vs 3.9±1.3 mg · kg−1 · min−1; p=0.044). In these 18 patients a significant inverse relationship was found between erythrocyte sodium-lithium countertransport and insulin-mediated glucose disposal (r s=−0.62; p=0.003). Raised erythrocyte sodium-lithium countertransport appears to be associated with insulin insensitivity in Type 1 diabetes, even in the absence of hyperlipidaemia, hypertension and nephropathy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00399093
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