Influence of acute glycaemic level on measures of myocardial infarction in non-diabetic pigs.

OBJECTIVE: Patients with diabetes are at increased risk of experiencing myocardial infarction. The influence of the prevailing plasma glucose level on infarction and mortality after acute ischaemia is however unknown. The aim was to study the effect of the acute plasma glucose level on the myocardial infarction size in a closed-chest pig model. DESIGN: 38 non-diabetic pigs were randomised to hypoglycaemic (1.8-2.2 mmol/l; n = 15), normoglycaemic (5-7 mmol/l; n = 12) or hyperglycaemic glucose clamping (22-23 mmol/l; n = 11). After 30 min within glucose target myocardial infarction was induced for 30 min followed by reperfusion for 120 min. Hereafter the heart was double-stained to delineate infarction from viable tissue within the area at risk. RESULTS: Mean infarction size was 201 ± 35 mm(2) (mean ± SEM) in the hypoglycaemic group, 154 ± 40 mm(2) in the normoglycaemic group and 134 ± 40 mm(2) in the hyperglycaemic group, with no differences in infarction size, infarct/area at risk ratio or troponin T levels between the groups. There was no difference in incidence of ventricular fibrillation or mortality between the groups. CONCLUSION: No statistically significant associations were observed between the acute glycaemic level and measures of myocardial infarction, rates of ventricular fibrillation and subsequent premature death in the setting of acute ischaemia and reperfusion.

Infrared thermographic assessment of changes in skin temperature during hypoglycaemia in patients with type 1 diabetes.

AIMS/HYPOTHESIS: Hypoglycaemia is associated with reduced skin temperature (Ts). We studied whether infrared thermography can detect Ts changes during hypoglycaemia in patients with type 1 diabetes and how the Ts response differs between patients with normal hypoglycaemia awareness and hypoglycaemia unawareness. METHODS: Twenty-four patients with type 1 diabetes (ten aware, 14 unaware) were studied during normoglycaemia (5.0-6.0 mmol/l), hypoglycaemia (2.0-2.5 mmol/l) and during recovery from hypoglycaemia (5.0-6.0 mmol/l) using hyperinsulinaemic glucose clamping. During each 1 h phase, Ts was measured twice by infrared thermography imaging in pre-defined areas (nose, glabella and the five left fingertips), symptoms of hypoglycaemia were scored and blood was sampled. RESULTS: Ts decreased during hypoglycaemia on the nose and glabella. The highest decrements were recorded on the nose (aware: -2.6 °C, unaware: -1.1 °C). In aware patients, the differences in temperature were statistically significant on both nose and glabella, whereas there was only a trend in the unaware group. There was a significant difference in hypoglycaemia-induced temperature changes between the groups. Patients in the aware group had higher hypoglycaemia symptom scores and higher adrenaline (epinephrine) levels during hypoglycaemia. CONCLUSIONS/INTERPRETATION: The hypoglycaemia-associated decrement in Ts can be assessed by infrared thermography and is larger in patients with normal hypoglycaemia awareness compared with unaware patients.

Hypoglycemia-associated changes in the electroencephalogram in patients with type 1 diabetes and normal hypoglycemia awareness or unawareness.

Hypoglycemia is associated with increased activity in the low-frequency bands in the electroencephalogram (EEG). We investigated whether hypoglycemia awareness and unawareness are associated with different hypoglycemia-associated EEG changes in patients with type 1 diabetes. Twenty-four patients participated in the study: 10 with normal hypoglycemia awareness and 14 with hypoglycemia unawareness. The patients were studied at normoglycemia (5-6 mmol/L) and hypoglycemia (2.0-2.5 mmol/L), and during recovery (5-6 mmol/L) by hyperinsulinemic glucose clamp. During each 1-h period, EEG, cognitive function, and hypoglycemia symptom scores were recorded, and the counterregulatory hormonal response was measured. Quantitative EEG analysis showed that the absolute amplitude of the θ band and α-θ band up to doubled during hypoglycemia with no difference between the two groups. In the recovery period, the θ amplitude remained increased. Cognitive function declined equally during hypoglycemia in both groups and during recovery reaction time was still prolonged in a subset of tests. The aware group reported higher hypoglycemia symptom scores and had higher epinephrine and cortisol responses compared with the unaware group. In patients with type 1 diabetes, EEG changes and cognitive performance during hypoglycemia are not affected by awareness status during a single insulin-induced episode with hypoglycemia.