VARIABILITY OF BLOOD SUGAR LEVELS WITH AN AUTOMATED METHOD

Gestational diabetes from A to Z

Gestational diabetes mellitus (GDM) is defined as any degree of hyperglycaemia that is recognized for the first time during pregnancy. This definition includes cases of undiagnosed type 2 diabetes mellitus (T2DM) identified early in pregnancy and true GDM which develops later. GDM constitutes a greater impact on diabetes epidemic as it carries a major risk of developing T2DM to the mother and foetus later in life. In addition, GDM has also been linked with cardiometabolic risk factors such as lipid abnormalities, hypertensive disorders and hyperinsulinemia. These might result in later development of cardiovascular disease and metabolic syndrome. The understanding of the different risk factors, the pathophysiological mechanisms and the genetic factors of GDM, will help us to identify the women at risk, to develop effective preventive measures and to provide adequate management of the disease. Clinical trials have shown that T2DM can be prevented in women with prior GDM, by intensive lifestyle modification and by using pioglitazone and metformin. However, a matter of controversy surrounding both screening and management of GDM continues to emerge, despite several recent well-designed clinical trials tackling these issues. The aim of this manuscript is to critically review GDM in a detailed and comprehensive manner, in order to provide a scientific analysis and updated write-up of different related aspects.

Do the current standards for glucose tolerance testing in pregnancy represent a valid conversion of O'Sullivan's original criteria?

The venous plasma values for the 100 gm glucose tolerance test endorsed by the Second International Workshop-Conference on Gestational Diabetes represent an arbitrary conversion from O'Sullivan's original values. The latter were calculated from whole blood by means of the Somogyi-Nelson method. The factor used to convert the whole blood values to plasma glucose values was empirically derived in a population in whom pregnancy status was not stated. A conversion factor derived from a nonpregnant population may systematically overestimate plasma glucose concentration when applied to a pregnant population. Paired specimens obtained from 995 consecutive pregnant patients were analyzed by the Somogyi-Nelson method on whole blood and the glucose oxidase method on plasma. A conversion formula was derived and was used to estimate plasma glucose values and 95% confidence limits equivalent to whole blood values. Application of this formula yields plasma glucose oxidase glucose tolerance test values of fasting, 96 mg/dl; 1 hour, 172 mg/dl; 2 hours, 152 mg/dl, and 3 hours, 131 mg/dl. These values are all lower than those currently endorsed.

Subcutaneous fat in newborn infants of diabetic mothers: An indication of quality of diabetic control

Biceps, triceps, subscapular, and suprailiac skinfolds were measured in 40 newborn infants of diabetic mothers. Maternal fasting blood-glucose and mean blood-glucose in the third trimester correlated significantly with neonatal skinfold thickness. Skinfold measurement, when compared with a reference range for gestational age, may be a convenient way of assessing one effect of maternal diabetes on the fetus. Gluteal adipose-cell diameter was measured in 31 infants of diabetic mothers. The fattest babies had the largest adipose cells and there was a significant positive correlation between maternal fasting blood-glucose and neonatal adipose cell diameter. These findings are consistent with the hypothesis that in diabetic pregnancy fetal hyperglycaemia and hyperinsulinism stimulate increased triglyceride synthesis in adipose cells and enlargement of adipose cells and lead to an increase in fetal subcutaneous fat.