Background and aims: Changes in the physiological tremor (PT) occurs with increased adrenaline levels in response to hypoglycaemia. They could be utilized to provide a non-invasive warning of hypoglycaemia.
Materials and methods: 12 type 1 diabetic subjects of whom 6 were hypoglycaemic aware (age 45 yrs, HbA1c 8.3%), 6 hypoglycaemic unaware (age 49.3 yrs, HbA1c 9%) and 6 non-diabetic controls (age 36.1 yrs) had an induced hypoglycaemia. The PT power ( cm/sec²)² and frequency were detected by an accelerometer taped to the middle finger.
Results: ( mean ± SE). Symptomatic hypoglycaemia at a mean glucose of 2.9mmol (range 3.8 to 2.7mmol) occurred in all 3 groups.
Power in the elevated arm in all groups correlated (p 0.0001) with the decrease in glucose, increasing by 350% from base line in the aware group, 120% in the unaware, and by 200% in controls. In the resting arm power was deceased. Tremor frequency did not change significantly in any of the groups.
The adrenaline levels for controls, basal 36.6 pg/ml ± 4.88, peak 232 pg/ml ± 10.1 correlated with decreased glucose levels (ANOVA)(p. 0.015) as in the aware group with a basal 48.1 pg/ml ± 25.9 , peak 690 pg/ml ± 28.6 (p 0.004). In the unaware group, it was noradrenaline that correlated (p 0.02) with decreased glucose levels, basal 348.9 pg/ml ± 59.4, peak 701.4 pg/ml ± 49 but not adrenaline. Noradrenaline in the aware and control group showed no correlation with decreased glucose levels
Systolic BP, pulse rate had a non-significant increase with hypoglycaemia and diastolic B P had a non-significant decrease.
Conclusions: There was a significant increase in power in both the elevated and resting arm, which may allow the PT to be used as an indicator for hypoglycaemia.
The physiological responses to hypoglycaemia in the unaware group was to the increased noradrenaline levels not adrenaline.