The metabolic response to hyperglycaemic clamping in insulin-dependent diabetes

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Abstract
The metabolic and hormonal effects of stable hyperglycaemia (10–12 mmol/l) have been examined in five insulin-dependent diabetics and compared with the results of 8 h (1200 to 2000 h) normoglycaemic (5–6 mmol/l) clamping. Glucose levels were maintained using a glucose controlled insulin infusion system. Mean blood lactate, pyruvate, total ketone bodies, glycerol and plasma nonesterified fatty acids were similar during the period of stable glycaemia at the two glucose levels. In contrast mean blood alanine was markedly elevated during hyperglycaemic clamping (0.384 ± 0.008 vs 0.298 ± 0.021 mmol/l) and 3-hydroxybutyrate was slightly decreased (0.068 ± 0.007 vs 0.084 ± 0.008 mmol/l). Plasma glucagon levels were raised during hyperglycaemic clamping and growth hormone slightly decreased. There was a close positive correlation between mean blood alanine and mean blood glucose (r = 0.79, p < 0.01), and a negative correlation of alanine with the amount of insulin infused (r =-0.72, p < 0.01). It is suggested that the raised alanine results from increased peripheral glucose utilisation. In general a short period of stable hyperglycaemia is not associated with a worsening of metabolic abnormalities in insulin-dependent diabetic subjects.