Glucose effectiveness and its components in relation to body mass index

Area of Science:

• Metabolic Physiology
• Endocrinology
• Obesity Research

Background:

• Obesity is linked to reduced insulin sensitivity (S_I), affecting glucose tolerance.
• The impact of obesity on glucose effectiveness (S_G), the insulin-independent component, is less understood.
• This study investigates S_G and its components across different body mass index (BMI) categories.

Purpose of the Study:

• To analyze glucose effectiveness (S_G) and its components in lean, overweight, and obese individuals.
• To determine how BMI categories influence the insulin-independent aspects of glucose metabolism.
• To assess the relationship between BMI and S_G and its sub-components (GEZI, BIE).

Main Methods:

• Cross-sectional study involving three BMI groups: Lean (LE), Overweight (OW), and Obese (OB).
• Subjects underwent a 3-hour frequently sampled intravenous glucose tolerance test (FSIGT).
• Minimal model analysis was used to calculate S_G, glucose effectiveness at zero insulin (GEZI), and basal insulin effect (BIE).

Main Results:

• Glucose effectiveness (S_G) was significantly reduced in overweight and obese individuals compared to lean individuals.
• S_G showed a significant inverse correlation with BMI (r = -0.3, P < 0.0001).
• No significant difference in S_G was observed between obese and overweight groups, or between Obese I and Morbidly Obese subgroups. Glucose effectiveness at zero insulin (GEZI) followed similar trends, while basal insulin effect (BIE) did not differ significantly across groups.

Conclusions:

• Glucose effectiveness (S_G) and its primary component, GEZI, deteriorate in overweight individuals compared to those with normal BMI.
• Further increases in BMI beyond 30 kg m^-2 do not lead to a significant additional decline in S_G.
• The findings highlight that the impairment of insulin-independent glucose disposal begins at lower BMI thresholds.