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Type 2 diabetes weakens immune function

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February 15, 2019

Adults with type 2 diabetes have lower natural killer cell activity compared with those with normal glucose tolerance or prediabetes, according to findings published in the Journal of Diabetes Investigation.

“The chronic inflammatory state in diabetes patients might be involved in the impaired immune function and, consequently, the higher susceptibility to infection,” Ji Sun Nam, MD, of the Severance Institute for Vascular and Metabolic Research at Yonsei University College of Medicine in Seoul, South Korea, and colleagues wrote. “Natural killer cell activity, in particular, has been shown to be involved in the immune dysfunction and increased risk of cancer in diabetes patients.”

Nam and colleagues conducted a cross-sectional study of 49 adults with type 2 diabetes (n = 21; mean age, 60.7 years; 61.9% women), prediabetes (n = 15; mean age, 58.8 years; 66.7% women) or normal glucose tolerance (n = 13; mean age, 53.7 years; 69.2% women) from the Endocrinology and Diabetes Center of Gangnam Severance Hospital in Seoul, South Korea. Each participant visited the center at least once between April and June 2017.

Levels of HbA1c, serum glucose, cholesterol, triglyceride, HDL cholesterol, LDL cholesterol, insulin and C-peptide were measured via fasting blood samples, and a 75-g oral glucose tolerance test also measured postload glucose, insulin and C-peptide. Activity of the natural killer cells, which are cytotoxic lymphocytes, was assessed based on measuring secreted interferon-gamma from the cells themselves.

The researchers found that participants with type 2 diabetes had lower mean natural killer cell activity (768.01) compared with participants with prediabetes (2,396.08) and participants with normal glucose tolerance (2,435.31; P < .001). In addition, in the entire cohort, fasting plasma glucose (P < .001), 2-hour plasma glucose (P < .001) and HbA1c (P < .001) all had negative correlations with natural killer cell activity, whereas there was a positive correlation between natural killer cell activity and insulin (P = .023) and beta-cell function (P < .001).

Among participants with type 2 diabetes, FPG (P = .002), 2-hour plasma glucose (P < .001) and HbA1c (P < .001) had negative correlations and beta-cell function (P = .005) had a positive correlation with natural killer cell activity.

The researchers also carried out multiple regression analysis, which confirmed that HbA1c (P < .001) and beta-cell function (P = .024) were independently associated with natural killer cell activity, whereas decreased activity was independently associated with HbA1c in participants with type 2 diabetes only (P < .001).

“The study supports the hypothesis that the increasing prevalence of infectious diseases

and malignancy in type 2 diabetes patients is associated with decreased immune function,” the researchers wrote. “Future efforts are required to redefine the relationship between type 2 diabetes mellitus and [natural killer] cell activity, and to provide a way to reduce the incidence of infectious diseases and cancer by carrying out large-scale studies of patients with type 2 diabetes.” – by Phil Neuffer

Disclosures: The authors report no relevant financial disclosures.

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