Serum insulin, proinsulin, and proinsulin/insulin ratio in type 2 diabetic patients / 대한내과학회지

ABSTRACT

BACKGROUND: Although insulin resistance and decreased insulin secretion are characteristics of establised type 2 DM, which of these metabolic abnormalities is the primary determinant of type 2 DM is controversial. It is also not well known how insulin resistance and beta cell dysfunction influence serum insulin, proinsulin, proinsulin/insulin ratio in type 2 DM. METHODS: We compared serum insulin, proinsulin, proinsulin/insulin ratio in type 2 diabetic patients and control subjects. We investigated the relationship between serum insulin, proinsulin, proinsuolin/insulin ratio and several biochemical markers which represent insulin resistance or beta cell function. RESULTS: Proinsulin, total insulin, and proinsulin/insulin ratio were significantly higher in type 2 DM than control(p< 0.001). In diabetic patients, proinsulin was correlated with fasting c-peptide(r=0.43, p=0.002), postprandial 2 hour blood glucose(r=0.213, p=0.05), and triglyceride(r=0.28, p=0.022). Total insulin was correlated with urinary albumin excretion rates(r=0.224, p=0.025) and body mass index(r=0.269, p=0.014). Proinsulin/insulin ratio was positively correlated with fasting c-peptide(r=0.236, p=0.031), fasting blood glucose(r=0.264, p=0.015), postprandial 2 hour blood glucose(r=0.277, p=0.001), and triglyceride(r=0.428, p< 0.001). In control subjects, fasting insulin was correlated with triglyceride (r=0.366, p=0.002). Proinsulin/insulin ratio was correlated with age(r=0.241, p=0.044). CONCLUSION: The serum levels of insulin and proinsulin seems to be associated with several markers of insluin resistance. The proinsulin/insulin ratio might represent beta cell function rather than insulin resistance. But more studies are needed to clarify the mechanism of elevated proinsulin/insulin ratio in type 2 DM.