Increased Metabolic Disorders and Impaired Insulin Secretory Function in the First-Degree Relatives of Type 2 Diabetic Patients with Normal Glucose Tolerance.

OBJECTIVE: To compare the metabolic status and pancreatic β-cell function in first-degree relatives (FDRs) of type 2 diabetic patients with normal glucose tolerance (NGT).

MATERIALS AND METHODS: Three hundred twelve subjects, who were NGT-FDR of type 2 diabetic patients and 1348 subjects, who were NGT individuals with no family history of diabetes, were defined as NGT-FDRs and NGT-controls (NGT-C), respectively. Blood pressure, body weight, waist circumference, plasma glucose, lipid profile, and insulin levels were measured in all subjects. Homeostasis model assessment of insulin resistance (HOMA-IR), HOMA-β, insulin sensitivity index (ISI), and disposition index (DI) was used to evaluate insulin resistance and insulin sensitivity.

RESULTS: The HOMA-IR and HOMA-β indices were significantly higher in the NGT-FDR group relative to the NGT-C, while the ISI, DI, and ΔI30 /ΔG30 were lower (P < 0.05). The prevalence rate of greater than or equal to three metabolic disorders was higher in the NGT-FDR group compared to the NGT-C (P < 0.05). In the NGT-FDR group, compared to people with normal metabolism, HOMA-β decreased when there was only one metabolic disorder, increased slightly when there were two to three metabolic abnormalities, and decreased again when there were four or more metabolic abnormalities. The data also indicated that having a family history of type 2 diabetes maybe an independent risk factor of β-cell dysfunction.

CONCLUSIONS: Metabolic disorders developed frequently in the NGT-FDRs of type 2 diabetic patients. As the number of coexisting metabolic disorders increased, pancreatic β-cell secretory ability and insulin sensitivity decreased. Therefore, it is necessary to provide early preventive interventions and monitoring of metabolic indices for NGT-FDRs of type 2 diabetic patients.