Effect of obesity and insulin on immunity in non-insulin-dependent diabetes mellitus

Objective: To understand the effect of obesity and insulin on immune functions in non-insulin-dependent diabetes mellitus (NIDDM). Subject: Fourteen obese NIDDM (body mass index (BMI) = 30.6 +/- 1.1), seven non-obese NIDDM (BMI = 24.2 +/- 0.5) and five obese non-NIDDM (BMI = 28.3 +/- 0.67). Interventions: We first examined the influence of insulin on the proliferation of several human cell lines. Second, we compared several immune functions between obese and non-obese NIDDM, and obese non-NIDDM patients using peripheral blood mononuclear cells. Result: Insulin decreased proliferation of T-cell lines but not that of other types of cell lines. Furthermore, obesity augmented the production of IL-1beta which could have cytotoxity against islet beta cells in NIDDM. Conclusion: Our data suggested that the pathophysiology of NIDDM could be affected by the change of immunity due to obesity, and the treatment of obesity in NIDDM may be important from an immunological aspect.