Braatvedt G D, Drury P L, Cundy T
Department of Medicine, University of Auckland.
N Z Med J. 1997 Dec 12;110(1057):459-62.
Glycated haemoglobin (HbA1C) has become the internationally established method of assessing long term glycaemic control in people with diabetes. In New Zealand the measurement of glycated albumin (fructosamine), which is substantially cheaper than HbA1C has been widely adopted. In this study we have sought to determine if the value of HbA1C can be reliably estimated from knowledge of plasma fructosamine.
Fifty subjects with diabetes and stable glycaemic control as assessed by 3-5 simultaneous measurements of HbA1C and fructosamine made sequentially over a median of 6 months, were studied. The relationship between the two measures was assessed by determining 95% prediction intervals for HbA1C from the regression equation relating mean HbA1C and fructosamine. A further 8 subjects with significantly changing glycaemic control were also studied.
Mean stable plasma fructosamine and HbA1C measurements were closely correlated (r = 0.661, p < 0.0001) with HbA1C increasing on average 1% for every 56 mumol L-1 increase in fructosamine. The prediction intervals for HbA1C were however wide. Thus at a plasma fructosamine of 350 mumol L-1 the 95% prediction intervals for HbA1C ranged from 6.6 to 11.2% (3 to 11 standard deviations above the mean of the normal reference range). This variability could not be accounted for by the presence of albuminuria or by the exclusion of those subjects with the greatest variability in fructosamine. In the subjects showing changes in glycaemic control, a change in HbA1C of 1% was associated with a change in fructosamine of between 29 and 63 mumol L-1.
Fructosamine levels generally correlate well with HbA1C within a population but the value of HbA1C in an individual cannot be inferred with any reliability from the level of fructosamine, nor can the change in HbA1C be inferred from the change in fructosamine. We suggest that if fructosamine is to be used as an index of glycaemic control in diabetes, it is supplemented by a measurement of HbA1C when fructosamine measurements are stable, in order to determine whether the given value of fructosamine is consistent with the glycaemic control targets for that individual.
糖化血红蛋白（HbA1C）已成为国际上评估糖尿病患者长期血糖控制的既定方法。在新西兰，糖化白蛋白（果糖胺）的检测方法因其成本远低于HbA1C而被广泛采用。在本研究中，我们试图确定是否可以通过血浆果糖胺值可靠地估算HbA1C值。
对50名糖尿病患者进行了研究，这些患者的血糖控制稳定，通过在6个月的中位数时间内连续3 - 5次同时测量HbA1C和果糖胺来评估。通过根据平均HbA1C与果糖胺的回归方程确定HbA1C的95%预测区间，评估这两种测量方法之间的关系。还对另外8名血糖控制显著变化的患者进行了研究。
平均稳定血浆果糖胺和HbA1C测量值密切相关（r = 0.661，p < 0.0001），果糖胺每增加56 μmol/L，HbA1C平均增加1%。然而，HbA1C的预测区间很宽。因此，在血浆果糖胺为350 μmol/L时，HbA1C的95%预测区间为6.6%至11.2%（比正常参考范围平均值高3至11个标准差）。这种变异性无法通过蛋白尿的存在或排除果糖胺变异性最大的受试者来解释。在血糖控制发生变化的受试者中，HbA1C变化1%与果糖胺变化29至63 μmol/L相关。
在人群中，果糖胺水平通常与HbA1C密切相关，但不能根据果糖胺水平可靠地推断个体的HbA1C值，也不能根据果糖胺的变化推断HbA1C的变化。我们建议，如果将果糖胺用作糖尿病血糖控制的指标，在果糖胺测量稳定时，应辅以HbA1C测量，以确定给定的果糖胺值是否与该个体的血糖控制目标一致。
