Diurnal variation in insulin binding to human monocytes

Area of Science:

• Endocrinology
• Chronobiology
• Metabolic Research

Background:

• Insulin's role in glucose regulation is critical for metabolic health.
• Daily variations in metabolic processes, known as circadian rhythms, are increasingly recognized.

Purpose of the Study:

• To investigate the diurnal variation of insulin binding to monocytes in healthy young adults.
• To determine if diet and fasting influence this circadian rhythm of insulin binding.
• To explore the relationship between insulin binding changes and insulin sensitivity.

Main Methods:

• Monocytes were isolated from healthy young individuals undergoing a 24-hour study period.
• Insulin binding assays were performed on monocytes from subjects with normal diets and during total fasting.
• Circadian rhythmicity, binding affinity, and receptor concentration were analyzed.

Main Results:

• A distinct diurnal variation in cellular insulin binding was observed in normally fed individuals, with low binding in the afternoon and a peak in the early morning.
• Total fasting abolished this circadian rhythm, suggesting a diet-related influence.
• Changes in insulin binding were attributed to fluctuations in binding affinity, not receptor number.

Conclusions:

• Healthy young adults exhibit a circadian rhythm in monocyte insulin binding, primarily driven by changes in binding affinity.
• This rhythm is diet-dependent and closely mirrors known daily variations in insulin sensitivity and glucose tolerance.