It is known that glycation among various proteins is increased in diabetic patients compared with non-diabetic subjects. Currently, among these glycated proteins, glycated hemoglobin (HbA1C) is used as the gold standard index of glycemic control in clinical practice for diabetes treatment. However, HbA1C does not accurately reflect the actual status of glycemic control in some conditions where plasma glucose changes during short term, and in patients who have diseases such as anemia and variant hemoglobin. In comparison, another index of glycemic control, glycated albumin (GA), more accurately reflects changes in plasma glucose during short term and also postprandial plasma glucose. Although GA is not influenced by disorders of hemoglobin metabolism, it is affected by disorders of albumin metabolism. This review summarizes diseases and pathological conditions where GA measurement is useful. These include the status of glycemic control changes during short term, diseases which cause postprandial hyperglycemia, iron deficiency anemia, pregnancy, chronic liver disease (liver cirrhosis), chronic renal failure (diabetic nephropathy), and variant hemoglobin.

OBJECTIVE—A1C levels have been shown to be elevated in relation to glycemia in late pregnancy, although the precise mechanisms remain undetermined. We hypothesized that iron deficiency is involved in the A1C increase in late pregnancy. RESEARCH DESIGN AND METHODS—In study 1, A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were determined in 47 nondiabetic pregnant women not receiving iron supplementation who were divided into four groups according to gestational period (group I, 21–24 weeks; group II, 25–28 weeks; group III, 29–32 weeks; and group IV, 33–36 weeks). In study 2, these determinants were obtained at two gestational periods (20–23 weeks and 32–33 weeks) in 17 nondiabetic pregnant women. RESULTS—In study 1, A1C levels were higher in groups III and IV than those in groups I and II, whereas serum glycated albumin levels were not different among these four groups. Hemoglobin, mean corpuscular hemoglobin (MCH), serum transferrin saturation, and serum ferritin were lower in groups III and IV. A1C levels were negatively correlated with MCH, serum transferrin saturation, and serum ferritin. In study 2, A1C levels were significantly increased at gestational weeks 32–33 from those at weeks 20–23, whereas serum glycated albumin levels did not differ between the two gestational periods. MCH, serum transferrin saturation, and serum ferritin were decreased at gestational weeks 32–33. A1C levels showed a negative correlation with MCH, serum transferrin saturation, and serum ferritin. CONCLUSIONS—A1C levels were elevated in late pregnancy owing to iron deficiency. Serum glycated albumin may offer a better index for monitoring glycemic control in pregnancy.

OBJECTIVE: We have already reported that A1C is elevated because of iron deficiency in late pregnancy among nondiabetic pregnant women. This report examined whether the same phenomenon is observed in pregnant women with diabetes. RESEARCH DESIGN AND METHODS: This longitudinal study was conducted in 17 pregnant women with diabetes (20–35 weeks of pregnancy). A1C, serum glycated albumin, erythrocyte indexes, and iron metabolism indexes were measured. RESULTS: A1C levels were significantly increased in late pregnancy, whereas serum glycated albumin showed no significant changes. Glycated albumin/A1C ratio, mean corpuscular hemoglobin, serum transferrin saturation, and serum ferritin were significantly decreased in late pregnancy. Serum transferrin saturation showed a significant positive correlation with glycated albumin/A1C ratio. CONCLUSIONS: A1C levels, but not serum glycated albumin levels, are elevated in late pregnancy because of iron deficiency in diabetic women. Serum glycated albumin may offer an adequate marker for glycemic control during pregnancy.

Recently, it has become clear that mild abnormal glucose tolerance increases the incidence of perinatal maternal-infant complications, and so the definition and diagnostic criteria of gestational diabetes mellitus (GDM) have been changed. Therefore, in patients with GDM and pregnant women with diabetes mellitus, even stricter glycemic control than before is required to reduce the incidence of perinatal maternal-infant complications. Strict glycemic control cannot be attained without an indicator of glycemic control; this review proposes a reliable indicator. The gold standard indicator of glycemic control in patients with diabetes mellitus is hemoglobin A1c (HbA1c); however, we have demonstrated that HbA1c does not reflect glycemic control accurately during pregnancy because of iron deficiency. It has also become clear that glycated albumin, another indicator of glycemic control, is not influenced by iron deficiency and therefore might be a better indicator of glycemic control in patients with GDM and pregnant women with diabetes mellitus. However, large-population epidemiological studies are necessary in order to confirm our proposal. Here, we outline the most recent findings about the indicators of glycemic control during pregnancy including fructosamine and 1,5-anhydroglucitol.