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Summary
Gastrointestinal hormone secretin stimulation revealed that diabetic B cells have normal sensitivity. Obese subjects, however, showed an increased insulin response, suggesting a larger B cell mass in obesity.
Area of Science:
- Endocrinology
- Gastroenterology
- Metabolic Research
Background:
- Maturity-onset diabetes and obesity are associated with altered glucose metabolism.
- The role of gastrointestinal hormones like secretin in modulating insulin secretion in these conditions requires further elucidation.
Purpose of the Study:
- To investigate the effect of secretin on insulin secretion in normal weight and obese individuals, with and without maturity-onset diabetes.
- To compare the sensitivity of pancreatic B cells to secretin across different metabolic states.
Main Methods:
- Twenty-four participants (normals, obese, normal weight diabetics, obese diabetics) received intravenous secretin infusions at increasing doses.
- Radioimmunological insulin assays and blood glucose measurements were performed.
- Insulin dose-response curves were analyzed to determine D50 (the dose eliciting 50% of maximal response).
Main Results:
- Secretin stimulation increased insulin response in all groups, with identical D50 values (16 pmol/kg) across all groups, indicating normal B cell sensitivity to secretin in diabetics.
- Obese subjects exhibited a significant insulin response at lower secretin doses (0.9 pmol/kg) compared to normal weight subjects (3.6 pmol/kg).
- This suggests an increased pancreatic B cell mass in obese individuals.
Conclusions:
- Diabetic B cells demonstrate normal sensitivity to gastrointestinal hormone secretin.
- Obesity is associated with an enhanced insulin secretory capacity, likely due to an increased B cell mass.
- Secretin may play a role in modulating insulin secretion, with differential effects observed in obesity.