Severe hypoglycemia reduces the shivering threshold in rabbits

Area of Science:

• Physiology
• Endocrinology

Background:

• Previous research indicated a 1°C decrease in shivering threshold for every 100 mg/dL reduction in blood glucose in rabbits within the ≈90 to >300 mg/dL range.
• The impact of mild-to-severe hypoglycemia on shivering threshold remained unevaluated.

Purpose of the Study:

• To investigate the relationship between shivering threshold and blood glucose concentration in the mild-to-severe hypoglycemic range.
• To quantify the effect of hypoglycemia on thermoregulation.

Main Methods:

• Thirty-nine rabbits were divided into three groups: severe hypoglycemia (45-75 mg/dL), mild hypoglycemia (75-100 mg/dL), and control (saline infusion).
• Rabbits were cooled via colonic perfusion until shivering onset or esophageal temperature reached 34°C.

Main Results:

• The shivering threshold was 35.7±1.1°C in severe hypoglycemia, 37.0±0.7°C in mild hypoglycemia, and 37.9±1.0°C in controls.
• A linear relationship was observed: shivering threshold (°C) = 0.032 * [blood glucose (mg/dL)] + 34.1 (R²=0.45).
• A decrease of 31 mg/dL in blood glucose corresponded to a 1°C reduction in shivering threshold.

Conclusions:

• A linear correlation exists between blood glucose levels and shivering threshold across normoglycemic and hypoglycemic ranges.
• Hypoglycemia reduces the shivering threshold approximately three times more significantly than hyperglycemia, based on previous findings.