2-hour OGTT Research Articles

Intensive Glycemic Control Lowers Plasma Visfatin Levels in Patients with Type 2 Diabetes

Visfatin is an independent association factor for type 2 diabetes mellitus (T2DM). In order to evaluate the plasma visfatin levels and investigate whether plasma visfatin concentrations are altered by intensive glycemic control in patients with diabetes, we determined plasma visfatin concentrations and metabolic parameters in 53 newly diagnosed type 2 diabetic patients and 35 healthy controls. Visfatin levels were also investigated before and after intensive glycemic control for three months in subgroup of patients with T2DM. Plasma visfatin levels were significantly elevated in diabetic patients compared with healthy controls (p<0.001). Circulating visfatin concentration was associated with fasting plasma glucose (FPG), 2-hour OGTT plasma glucose (2hPG), HOMA-beta indexes (r=0.338, p=0.001; r=0.340, p=0.002; r=-0.296, p=0.006, respectively), but not with insulin sensitivity (HOMA-IR) or other metabolic or anthropometric parameters in all subjects. In addition, visfatin levels were also correlated with HbA1c levels in diabetic patients. Furthermore, visfatin concentrations reduced from 25.0+/-6.5 ng/ml at baseline to 20.3+/-4.7 ng/ml (p<0.01) after 3 months of intensive glycemic control, while HbA1c levels decreased from 9.0+/-1.8% to 6.2+/-0.7% (p<0.01). We conclude that the change of visfatin concentration may be a compensatory mechanism to ameliorate insulin deficiency due to pancreatic beta-cell dysfunction.

No acute effect of physiological insulin increase on dehydroepiandrosterone sulfate in women with obesity and/or polycystic ovarian disease

Conflicting information concerning the acute effect of hyperinsulinemia on circulating adrenal androgens, specifically DHEAS, is available. The effect of PCOD or obesity on this response is unclear. We prospectively examined the acute response of circulating DHEAS to the physiological rise in serum insulin after an OGTT in 10 women with PCOD (5 obese and 5 normal weight) and 10 ovulatory euandrogenic women (5 obese and 5 normal-weight). All underwent a standard 75-g 2-hour OGTT. Insulin and DHEAS were measured before and after OGTT. To control for the potential dilutional effects induced by hyperinsulinemia or hyperglycemia on intravascular tonicity, DHEAS levels were correlated to serum protein. As expected, the 2-hour insulin levels were significantly greater than baseline. No significant changes in circulating DHEAS or in the DHEAS to protein ratio was observed in any patient group 2 hours after glucose-induced hyperinsulinemia. The power of this study was greater than 89% for an alpha error of 0.05 and an expected change in DHEAS of 25%. In summary, it appears unlikely that acute increases in insulin within the physiological range are important in the regulation of circulating DHEAS in either PCOD or euandrogenic women, independent of obesity.

Oral glucose tolerance test in pregnancy. Evaluation of a simplified procedure.

After initial screening for gestational diabetes, 182 3-hour OGTTs in altogether 168 patients with determination of plasma glucose at 30-minute intervals were performed. Two-hour and 3-hour areas below the curve were calculated. Twenty-two patients had a reduced glucose tolerance test as judged by the 3-hour areas. Twenty of the 22 patients had a reduced glucose tolerance even according to the 2-hour areas. The correlation coefficient between the 3-hour areas and the 2-hour areas was 0.97. In 160 observations plasma glucose and capillary blood glucose were compared. The correlation coefficient between plasma glucose and capillary blood glucose concentrations was 0.99. It is concluded that the discriminatory power of the 2-hour OGTT with capillary blood glucose determinations is comparable to that of the 3-hour OGTT with venous plasma glucose determinations. The simplicity of the suggested method makes it suitable for use in instances with moderate or small laboratory resources.