BACKGROUND: Although insulin resistance and decreased insulin secretion are characteristics of established 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 and proinsulin/insulin ratio in type 2 diabetic patients and control subjects. We also investigated the relationship between serum insulin, proinsulin and proinsulin/insulin ratio and several biochemical markers which represent insulin resistance or beta cell function. RESULTS: Insulin, proinsulin and proinsulin/insulin ratio were significantly higher in type 2 DM than control(p < 0.001). In diabetic patients, total insulin level was correlated with urinary albumin excretion rates(r = 0.224, p = 0.025) and body mass index(r = 0.269, p = 0.014). Proinsulin level 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). 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, insulin level 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 seem to be associated with several markers of insulin resistance. Whereas proinsulin/insulin ratio might represent beta cell function rather than insulin resistance. But more studies are needed to clarify the mechanisms of elevated proinsulin/insulin ratio in type 2 DM.
Aged ; Diabetes Mellitus, Non-Insulin-Dependent/etiology ; Diabetes Mellitus, Non-Insulin-Dependent/blood* ; Female ; Human ; Insulin/blood* ; Insulin Resistance* ; Islets of Langerhans/physiopathology* ; Male ; Middle Age ; Proinsulin/blood* ; Sulfonylurea Compounds/pharmacology

Most Korean patients with non-insulin-dependent diabetes mellitus (NIDDM) have been reported not to be obese, and many of them lost weight significantly during the course of their disease. In this regard, a retrospective cohort study was conducted to determine the relationship between body mass index (BMI, kg/m2) and the risk for NIDDM among Koreans. Subjects who had received a medical examination from 1990 to 1991 and who were available for the detection of NIDDM until September 1999 were included. Subjects who initially had diabetes or were diagnosed as diabetic within 1 yr after enrollment were excluded. We reviewed the medical records of final cohort of 2,531 subjects. Follow-up of this cohort revealed 117 cases with diabetes with an incident of 7.8 per 1,000 person-years. Compared with those with BMI less than 23 kg/m2, the adjusted relative risks for diabetes mellitus for those with BMI of 23-24.9, 25-26.9, and greater than 27 kg/m2 were 0.85 (0.47-1.50), 1.29 (0.72-2.31), and 3.38 (1.22-4.63), respectively, for men (p for trend<0.01) and as for 9.14 (1.99-41.8), 7.36 (1.47-36.8), and 14.5 (3.03-69.2), respectively, for women (p for trend<0.01). These data indicate a direct relationship between obesity and the risk for the development of diabetes, emphasizing the importance of weight control for the prevention of NIDDM in Koreans.
Adolescence ; Adult ; Aged ; Aged, 80 and over ; Body Mass Index ; Cohort Studies ; Diabetes Mellitus, Non-Insulin-Dependent/*etiology ; Female ; Human ; Male ; Middle Age ; Obesity/*complications ; Retrospective Studies

The occurrence of immunoglobulin A nephropathy (IgAN) in patients with noninsulin dependent diabetes mellitus (NIDDM) is a rare event and of pathogenetic interest. It is not clear whether this is merely coincidence. We report here five patients with IgAN in NIDDM associated with or without diabetic glomerulosclerosis. All of the patients were Korean males. In three patients, diabetes mellitus was diagnosed at the same time with diagnosis of IgAN, and the known duration of the diabetes in the other two patients were three and seven years, respectively. There was no evidence of diabetic retinopathy in four patients, but it was found in one patient. In all cases, the diagnosis of IgAN was made by immunohistology.
Adult ; Biopsy ; Case Report ; Complement 3/analysis ; Diabetes Mellitus, Non-Insulin-Dependent/complications* ; Diabetic Nephropathies/pathology* ; Glomerular Mesangium/pathology ; Glomerulonephritis, IGA/pathology* ; Glomerulonephritis, IGA/etiology ; Human ; IgG/analysis ; Kidney Glomerulus/pathology ; Male ; Microscopy, Fluorescence ; Middle Age