Targets and tactics: the relative importance of HbA1c,fasting and postprandial plasma glucose levels to glycaemic control in type 2 diabetes

Background: The incidence of type 2 diabetes is reaching pandemic proportions, impacting patients and healthcare systems across the globe. Evidence suggests that a majority of patients are not achieving recommended blood glucose targets resulting in an increased risk of micro‐ and macro‐vascular complications. Aim: To review literature on the significance of glycosylated haemoglobin (HbA_1c), fasting plasma glucose (FPG) and postprandial plasma glucose (PPG), their inter‐relationships and relative importance in the treatment of diabetes, and to provide practical guidance on effective monitoring of patients. Methods: Clinical guidelines on diabetes management and clinical and preclinical studies of glycaemic control identified through a publications database search were reviewed. Results: Glycaemic control remains fundamental to the successful management of diabetes. HbA_1c is the gold standard measure of glycaemic control but recent evidence suggests that postmeal hyperglycaemia also plays an important role in the aetiology of diabetes‐associated complications and control of PPG levels is vital to the achievement of recommended HbA_1c targets. Conclusions: The call for action on type 2 diabetes has never been more compelling; with a clear focus on strategies for glycaemic control, the impact of the diabetes pandemic can be limited.     

2型糖尿病糖化血红蛋白与全天不同时间血糖水平的关系

目的探讨2型糖尿病患者糖化血红蛋白(HbA1c)与全天不同时间血糖水平的关系。方法171例2型糖尿病患者检测三餐前30min、餐后2h及晚睡前共7次血糖水平,并计算平均血糖水平(MBG),同时测定HbA1c。按HbA1c水平不同将患者分为2组血糖控制尚可组(HbA1c≤7.5%)和控制差组(HbA1c>7.5%)。直线回归相关分析总体及各组HbA1c与MBG、全天7次血糖的相关性。结果MBG与HbA1c呈显著正相关(r=0.851,P<0.001),MBG=-0.70+1.30×HbA1c;HbA1c与全天7次血糖水平均呈正相关,逐步多元线形回归分析示HbA1c与空腹、晚餐后、午餐后及早餐后血糖相关。HbA1c≤7.5%组的HbA1c与晚餐后、午餐后及午餐前血糖相关,而HbA1c>7.5%组HbA1c与空腹、晚餐后、午餐后及早餐后血糖相关。结论HbA1c受全天平均血糖水平的影响,血糖控制尚可组晚餐后、午餐后及午餐前的血糖对HbA1c影响明显,而血糖控制差组空腹、晚餐后、午餐后及早餐后的血糖对HbA1c影响明显。     

空腹血糖联合糖化血红蛋白检测对糖尿病筛查的临床意义

目的评价联合应用空腹血糖和糖化血红蛋白(HbA1c)检测对糖尿病筛查的临床价值。方法对8669名特定人群,同时进行空腹血糖和糖化血红蛋白(HbA1c)检测,所得数据进行对比分析。结果单独以空腹血糖大于等于6.1mmol/L筛查出的糖尿病风险人群为743人,占总检测人数的8.6%;单独以糖化血红蛋白(HbA1c)大于等于6%筛查出的糖尿病风险人群为627人,占总检测人数的7.2%;联合两种检测进行筛查,以两个指标中任何一个超过切点的都筛出来,可筛查出943人,风险筛出率为10.9%;通过统计学分析,差异有统计学意义(P﹤0.01)。结论空腹血糖或糖化血红蛋白(HbA1c)单个指标进行糖尿病风险筛查,都会有一部分可疑人群无法筛出,二者联合应用,可以筛查出更多处于糖尿病风险的可疑人群。     

Longitudinal trajectories of HbA1c and fasting plasma glucose levels during the development of type 2 diabetes: the Toranomon Hospital Health Management Center Study 7 (TOPICS 7)

OBJECTIVE

To describe the trajectory of HbA_1c and glucose concentrations before the diagnosis of diabetes.

RESEARCH DESIGN AND METHODS

The study comprised 1,722 nondiabetic Japanese individuals aged 26–80 years. Fasting plasma glucose (FPG) and HbA_1c were measured annually for a mean of 9.5 (SD 1.8) years.

RESULTS

Diabetes occurred in 193 individuals (FPG ≥7.0 mmol/L, self-reported clinician-diagnosed diabetes, or HbA_1c ≥6.5%). Mean HbA_1c values were >5.6% each year before diagnosis in diabetes cases. Mean HbA_1c (5.69% [95% CI 5.50–5.88]) was higher in the 21 individuals who developed diabetes 10 years after the baseline examination than in nondiabetic individuals after 10 years (5.27% [5.25–5.28]). From 3 years to 1 year prediagnosis, HbA_1c increased 0.09% (SE 0.01)/year, reaching 5.90% (5.84–5.96) 1 year prediagnosis. In the entire group, marked increases in HbA_1c of 0.3% (SE 0.05%)/year and FPG of 0.63 (0.07) mmol/L/year predicted diabetes.

CONCLUSIONS

HbA_1c trajectory increased sharply after gradual long-term increases in diabetic individuals.Trajectories of plasma glucose concentrations, insulin resistance, and insulin secretion to reflect the pathogenesis of type 2 diabetes were studied (1–8). Although HbA_1c is used to diagnose diabetes or indicate a prediabetic state in some countries (9), the long-term trajectory of HbA_1c before diabetes is little known. We retrospectively examined 10-year longitudinal data on apparently healthy Japanese individuals to investigate prediabetic changes in HbA_1c and compare such changes with those of fasting plasma glucose (FPG).     

Defining the relationship between plasma glucose and HbA(1c): analysis of glucose profiles and HbA(1c) in the Diabetes Control and Complications Trial

OBJECTIVE:To define the relationship between HbA(1c) and plasma glucose (PG) levels in patients with type 1 diabetes using data from the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: The DCCT was a multicenter, randomized clinical trial designed to compare intensive and conventional therapies and their relative effects on the development and progression of diabetic complications in patients with type 1 diabetes. Quarterly HbA(1c) and corresponding seven-point capillary blood glucose profiles (premeal, postmeal, and bedtime) obtained in the DCCT were analyzed to define the relationship between HbA(1c) and PG. Only data from complete profiles with corresponding HbA(1c) were used (n = 26,056). Of the 1,441 subjects who participated in the study, 2 were excluded due to missing data. Mean plasma glucose (MPG) was estimated by multiplying capillary blood glucose by 1.11. Linear regression analysis weighted by the number of observations per subject was used to correlate MPG and HbA(1c). RESULTS: Linear regression analysis, using MPG and HbA(1c) summarized by patient (n = 1,439), produced a relationship of MPG (mmol/l) = (1.98 . HbA(1c)) - 4.29 or MPG (mg/dl) = (35.6 . HbA(1c)) - 77.3, r = 0.82). Among individual time points, afternoon and evening PG (postlunch, predinner, postdinner, and bedtime) showed higher correlations with HbA(1c) than the morning time points (prebreakfast, postbreakfast, and prelunch). CONCLUSIONS: We have defined the relationship between HbA(1c) and PG as assessed in the DCCT. Knowing this relationship can help patients with diabetes and their healthcare providers set day-to-day targets for PG to achieve specific HbA(1c) goals.     

Combined use of fasting plasma glucose and HbA1c predicts the progression to diabetes in Chinese subjects

OBJECTIVE: We have previously suggested using the paired values of fasting plasma glucose (FPG) and HbA1c to identify potential diabetic subjects. In this article, we followed up on 208 nondiabetic subjects and examined their rates of progression to diabetes. We analyzed their likelihood of becoming diabetic according to their baseline FPG and HbA1c concentrations. RESEARCH DESIGN AND METHODS: Between 1988 and 1995, 2,877 Chinese subjects with risk factors for diabetes underwent screening. Of these, 2,250 had FPG <7.8 mmol/l and 2-h plasma glucose (PG) <11.1 mmol/l. Of these 2,250 subjects, 265 were randomly recruited for an annual oral glucose tolerance test (OGTT) until they progressed to develop diabetes. Of those 265 subjects, 57 had baseline FPG > or =7.0 mmol/l and were excluded from the present analysis. Hence, the progression of glucose tolerance in 208 subjects who were nondiabetic according to the new American Diabetes Association diagnostic criteria (FPG < 7.0 mmol/l and 2-h PG < 11.1 mmol/l) was examined RESULTS: Of the 208 nondiabetic subjects, 26 (12.5%) were men and 182 (87.5%) were women. After a mean follow-up of 1.60 +/- 1.16 years (range 1-7, median 1), 44 (21.2%) progressed to develop diabetes and 164 (78.8%) remained nondiabetic. Those who were diabetic at the end of the study had a high likelihood ratio (LR) of 9.3 to have baseline FPG > or =6.1 mmol/l and baseline HbA1c > or =6.1%. This was compared with a low LR of 0.6-1.1 in diabetic subjects who had either FPG <6.1 mmol/l or HbA1c <6.1% or both at baseline. The crude rate of progression to diabetes was more than five times higher (44.1 vs. 8.1%) in those whose baseline FPG was > or =6.1 mmol/l and baseline HbA1c was > or =6.1% compared with those whose baseline FPG was <6.1 mmol/l and baseline HbA1c was <6.1%. CONCLUSIONS: For Chinese subjects with risk factors for glucose intolerance, the use of paired FPG and HbA1c values helped to identify potential diabetic subjects. Those with an FPG > or =6.1 mmol/l and HbA1c > or =6.1% had a rate of progression to diabetes more than five times higher than those with an FPG <6.1 mmol/l and an HbA1c <6.1% after a mean follow-up of 1.6 years. Those with an FPG > or =6.1 but <7.0 mmol/l, especially if their HbA1c was > or =6.1%, should undergo an OGTT to confirm diabetes. Subjects with an FPG <6.1 mmol/l and/or an HbA1c <6.1% should have regular screening using the paired values of FPG and HbA1c.     

Contributions of fasting and postprandial plasma glucose increments to the overall diurnal hyperglycemia of type 2 diabetic patients: variations with increasing levels of HbA(1c)

OBJECTIVE: The exact contributions of postprandial and fasting glucose increments to overall hyperglycemia remain controversial. The discrepancies between the data published previously might be caused by the interference of several factors. To test the effect of overall glycemic control itself, we analyzed the diurnal glycemic profiles of type 2 diabetic patients investigated at different levels of HbA(1c). RESEARCH DESIGN AND METHODS: In 290 non-insulin- and non-acarbose-using patients with type 2 diabetes, plasma glucose (PG) concentrations were determined at fasting (8:00 A.M.) and during postprandial and postabsorptive periods (at 11:00 A.M., 2:00 P.M., and 5:00 P.M.). The areas under the curve above fasting PG concentrations (AUC(1)) and >6.1 mmol/l (AUC(2)) were calculated for further evaluation of the relative contributions of postprandial (AUC(1)/AUC(2), %) and fasting [(AUC(2) - AUC(1))/AUC(2), %] PG increments to the overall diurnal hyperglycemia. The data were compared over quintiles of HbA(1c). RESULTS: The relative contribution of postprandial glucose decreased progressively from the lowest (69.7%) to the highest quintile of HbA(1c) (30.5%, P < 0.001), whereas the relative contribution of fasting glucose increased gradually with increasing levels of HbA(1c): 30.3% in the lowest vs. 69.5% in the highest quintile (P < 0.001). CONCLUSIONS: The relative contribution of postprandial glucose excursions is predominant in fairly controlled patients, whereas the contribution of fasting hyperglycemia increases gradually with diabetes worsening. These results could therefore provide a unifying explanation for the discrepancies as observed in previous studies.     

Drug titration patterns and HbA1c levels in type 2 diabetes

Objective: To evaluate oral antidiabetes drug (OAD) use, haemoglobin A_1c (HbA_1c) testing and glycaemic control in type 2 diabetes patients. Study design: Retrospective analysis based on claims data from the Integrated Healthcare Information Services (IHCIS) National Managed Care Benchmark Database. Methods: OAD use and HbA_1c testing were analysed for patients with ≥ 2 claims indicating diagnosis of type 2 diabetes and ≥ 1 90‐day OAD treatment period between 1 January, 2000 and 30 June, 2006. Likelihood of HbA_1c testing was examined using multivariable logistic regression analyses, adjusting for OAD regimen and patients’ sociodemographical characteristics. Results: Patients were classified based on initial OAD regimen: metformin (MET) (n = 22,203; 41.3%), sulphonylurea (SFU) (n = 18,439; 34.3%), thiazolidinedione (TZD) (n = 7663; 14.3%), SFU + MET (n = 5467; 10.2%) and TZD + MET (n = 2355; 4.2%). A total of 51.5% of patients had HbA_1c testing during 90 days preceding OAD initiation through regimen completion. Approximately, 65% of MET and 58% of SFU patients had no titration of initial regimen. Patients demonstrating inadequate glucose control decreased from 68.5% at baseline to 46.9% within 90 days of regimen initiation. Multivariable logistic regression indicated several negative predictors of HbA_1c testing, including SFU use, age 65+ years, moderate insurance copayment and preindex inpatient utilisation. Multivariable logistic regression of variables associated with reduced likelihood of up‐titration included TZD, SFU + MET, or TZD + MET treatment, age 18–34 years, Medicare insurance and any preindex healthcare utilisation. Conclusions: Patients are not being transitioned to additional OADs in a stepwise fashion and/or are receiving inadequate titration on current OAD regimens. The low rate of HbA_1c testing and rates of control are contributing factors.     

Using HbA(1c) to improve efficacy of the american diabetes association fasting plasma glucose criterion in screening for new type 2 diabetes in American Indians: the strong heart study

OBJECTIVE: To find an optimal critical line in the fasting plasma glucose (FPG)-HbA(1c) plane for identifying diabetes in participants with impaired fasting glucose (IFG) and thereby improve the efficacy of using FPG alone in diabetes screening among American Indians. RESEARCH DESIGN AND METHODS: We used FPG, 2-h postload glucose (2hPG), and HbA(1c) measured in the 2,389 American Indians (aged 45-74 years, without diabetes treatment or prior history of diabetes) in the Strong Heart Study (SHS) baseline (second) examination. Participants were classified as having diabetes if they had either FPG > or =126 mg/dl or 2hPG > or =200 mg/dl, as having IFG if they had 110 < or = FPG < 126 mg/dl, and as having normal fasting glucose (NFG) if they had FPG <110, according to the American Diabetes Association (ADA) definition. Logistic regression models were used for identifying diabetes (2hPG > or =200 mg/dl) in IFG participants. The areas under the receiver operating characteristic (ROC) curves generated by different logistic regression models were evaluated and compared to select the best model. A utility function based on the best model and the cost-to-benefit ratio was used to find the optimal critical line. The data from the second examination were used to study the effect of the time interval between the successive diabetes screenings on both the FPG criterion and the optimal critical line. RESULTS: A total of 37% of all subjects with new diabetes at baseline and 55.2% of those in the second exam had 2hPG > or =200 but FPG <126. There was a very large portion of IFG participants with diabetes (19.3 and 22.9% in the baseline and second exam, respectively). Among the areas under the ROC curves, the area generated by the logistic regression model on FPG plus HbA(1c) is the largest and is significantly larger than that based on FPG (P = 0.0008). For a cost-to-benefit ratio of 0.23888, the optimal critical line that has the highest utility is: 0.89 x HbA(1c) + 0.11 x FPG = 17.92. Those IFG participants whose FPG and HbA(1c) were above or on the line were referred to take an oral glucose tolerance test (OGTT) to diagnose diabetes. The optimal critical line is lower if a successive diabetes screening will be conducted 4 years after the previous screening. CONCLUSIONS: FPG > or =126 and 2hPG > or =200, as suggested by the ADA, are used independently to define diabetes. The FPG level is easy to obtain, and using FPG alone is suggested for diabetes screening. It is difficult to get physicians and patients to perform an OGTT to get a 2hPG level because of the many drawbacks of the OGTT, especially in those patients who already have FPG <126. It is also impractical to conduct an OGTT for everyone in a diabetes screening. Our data show that 37% of all subjects with new diabetes in the SHS baseline exam and 55.2% of those in the second exam have 2hPG > or =200 but FPG <126. These cases of diabetes cannot be detected if FPG is used alone in a diabetes screening. Therefore, although the small portion of diabetes in the NFG group (4.7% in the baseline and 6.9% in the second exam) may be ignored, those cases of diabetes among IFG participants ( approximately 20% in our data) need further consideration in a diabetes screening. It may be worthwhile for those IFG participants identified by the optimal critical line to take an OGTT. The optimal critical line and time interval between successive diabetes screenings need further study.     

HbA_(1c)诊断2型糖尿病特性观察及在空腹血糖正常人群中的分布特征研究

目的观察糖化血红蛋白(HbA1c)诊断2型糖尿病(T2DM)的特点及其在空腹血糖(FPG)正常者中的分布情况。方法同时测定729例FPG正常者尿酸(UA)、甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C);用免疫抑制比浊法测定247例接受口服葡萄糖耐量试验(OGTT)者(包括T2DM 164例、糖耐量受损41例、空腹血糖受损18例、糖耐量正常者24例)的HbA1c,以OGTT和临床诊断结果作为标准,绘制HbA1c和FPG的受试者工作特征(ROC)曲线,确定HbA1c诊断T2DM的切点,通过对比分析观察不同性别及同性别不同年龄组中HbA1c的分布情况。结果免疫抑制比浊法测定HbA1c诊断T2DM的切点为6.36%,诊断灵敏度为86.50%、特异性为90.60%、阳性预测值为94.63%、阴性预测值为76.50%、曲线下面积为0.944[95%可信区间(CI):0.917~0.971],FPG7.0 mmol/L时诊断糖尿病的灵敏度为85.90%、特异性为93.80%、曲线下的面积为0.957[95%CI:0.932~0.981]。FPG正常者中女性HbA1c、HDL-C水平明显高于男性(P=0.000),男性血红蛋白(Hb)、FPG、UA、TG水平高于女性(P值分别为0.000、0.020、0.000、0.000)。随着年龄的增加,男、女性HbA1c、FPG、TC和LDL-C均有增高的趋势;特别是在60岁以后,女性HbA1c升高更高明显;但HDL-C在男性中有上升的趋势,在女性中有下降的趋势。结论免疫抑制比浊法测定HbA1c诊断T2DM的切点为6.36%,随着年龄的增加要定期测定HbA1c,以达到预防糖尿病的目的。     

Normal fasting plasma glucose and risk of type 2 diabetes

OBJECTIVE

To investigate the association of normal fasting plasma glucose (FPG) and the risk for type 2 diabetes.

RESEARCH DESIGN AND METHODS

Data concerning 13,845 subjects, aged 40–69 years, who had their FPG measured at least three times between 1992 and 2008 were extracted from a database. Three FPG groups were defined (51–82, 83–90, and 91–99 mg/dL). A Cox proportional hazards analysis was applied to estimate the risk of incident diabetes adjusted for other risk factors.

RESULTS

During 108,061 person-years of follow-up (8,110 women and 5,735 men), 307 incident cases of type 2 diabetes were found. The final model demonstrated a hazard ratio of 2.03 (95% CI 1.18–3.50) for 91–99 mg/dL and 1.42 (0.42–4.74) for 83–90 mg/dL.

CONCLUSIONS

Our data suggest that FPG between 91 and 99 mg/dL is a strong independent predictor of type 2 diabetes and should be used to identify people to be further investigated and aided with preventive measures.The prevalence of type 2 diabetes is increasing worldwide (1,2). Prediction methods are a matter of discussion (3–5). A recent study (6) showed an alteration of normal linear trajectories for fasting and postload plasma glucose concentrations and insulin sensitivity and secretion 3–6 years before diagnosis. Other studies (7,8) showed an increased risk of developing type 2 diabetes among normoglycemic subjects, particularly in those with a fasting plasma glucose (FPG) range of 91–99 mg/dL. Clear information regarding Mediterranean populations is lacking. We investigated whether the higher tertiles of within-normal-range FPG concentrations in a northern Italian population can help identify people at increased risk.     

空腹血葡萄糖及糖化血红蛋白检测在2型糖尿病诊断中的应用比较

目的:比较空腹血葡萄糖(FPG)和糖化血红蛋白(HbA1c)在2型糖尿病(2DM)诊断中的意义。方法:对188例未诊断为2DM的对象同时检测FPG和HbA1c。分别按1999年世界卫生组织(WHO)诊断糖尿病标准(FPG≥7.0 mmol/L)和美国糖尿病协会(ADA)新标准(HbA1c≥6.5%),对研究对象分别进行分组(2DM和非2DM组),比较2个检测指标在诊断2DM中的差异。以FPG为诊断2DM的金标准,计算HbA1c诊断2DM的灵敏度、特异度、预测值、似然比等诊断性能。结果:FPG均值在2种标准诊断的2DM患者之间差异有统计学意义(P0.05)。HbA1c均值在2种标准诊断的2DM患者间差异无统计学意义(P>0.05),在2种标准诊断的非2DM患者间差异有统计学意义(P<0.05)。HbA1c≥6.5%诊断糖尿病的灵敏度(S)为100%,特异度(Sp)为93%,阴性似然比(-LR)为0.00和阳性似然比(+LR)为14.29。结论:HbA1c诊断糖尿病有较高的诊断灵敏度和特异度。     

Receiver operating characteristic analysis on fasting plasma glucose, HbA1c, and fructosamine on diabetes screening.

OBJECTIVE: To determine the efficacy of HbA1c and fructosamine as alternatives to fasting plasma glucose (FPG) for diabetes screening. RESEARCH DESIGN AND METHODS: Receiver operating characteristic (ROC) analysis was conducted on the above tests. Comparison among tests was based on the area under ROC curve of a test. World Health Organization criteria for classifying glucose tolerance status of the subjects was used. The study consisted of subjects (n = 583) who visited the clinic from September to October 1989 and all diabetic cases (n = 36) from November 1989 to March 1990, after excluding those less than 40 yr of age or with hypoglycemic therapies (469 were normal, 88 with impaired glucose tolerance ( IGT], and 62 with diabetes). RESULTS: Area under ROC curve of HbA1c was not different from that of FPG. Area under curve of fructosamine was significantly smaller than that of FPG. For all tests, overall efficacy of a test to detect IGT and diabetes was considerably diminished compared with detection of diabetes alone. CONCLUSIONS: The discriminating ability of HbA1c is almost the same as that of FPG, therefore HbA1c is a good alternative to FPG. Fructosamine is not suitable for diabetes screening.     

糖化血红蛋白联合空腹血糖筛查2型糖尿病高危人群的临床意义

目的了解糖化血红蛋白(HbA1c)筛查糖尿病和糖代谢受损的敏感性并与空腹血糖(FBG)进行比较。方法对400例无糖尿病病史的糖尿病高危人群同时检测FBG和HbA1c,据空腹血糖水平分为三组:A1组:FBG<6.1 mmol/L,计336例,A2组:FBG 6.1-6.9 mmol/L,45例,A3组FBG≥7.0 mmol/L,19例。结果 (1)400例人群中,HbA1c≥6.0%,88例,异常率为22.0%;FBG≥6.1mmol/L,54例,异常率13.5.%,HbA1c的异常率高于FBG,P<0.05。(2)A1组HbA1c>≥6.0%,29例,占8.6%;A2组HbA1c≥6.0%,41例,占91.1%;A3组HbA1c≥6.0%,18例,占94.7%;(3)400例人群中,HbA1c≥6.0%或FBG≥6.1mmol/L,93例,异常率23.3%%。结论 HbA1c筛查糖尿病高危人群血糖异常的敏感性高于空腹血糖,两者联合检查有助发现更多糖代谢异常的患者。     

The calculated versus the measured glycosylated haemoglobin (HbA1c) levels in patients with type 2 diabetes mellitus

BackgroundDiabetes mellitus (DM) is a chronic metabolic disorder that is increasing globally. It is associated with chronic complications that are more common among patients with poor glycaemic control. Glycosylated haemoglobin (HbA_1c) is the gold standard for monitoring glycaemic control. Measurements of HbA_1c are relatively expensive and not available in some remote areas of developing countries.MethodsWe conducted a cross‐sectional study to evaluate the agreement between the calculated and measured HbA_1c levels. The equation to compute the calculated HbA_1c also incorporated the fasting blood glucose (FBG) level and was as follows: HbA_1c = 2.6 + 0.03 × FBG (mg/dl).ResultWe enrolled 290 patients with type 2 DM in this study. Of these, 204 (70.3%) were females and the mean (SD) age was 54.9 (12.8) years. The mean (SD) diabetes duration was 6.8 (5.5) years. There were 211 (72.8%) patients using oral hypoglycaemic agents, 62 (21.4%) were using insulin and 17 (5.9%) were using both insulin and oral hypoglycaemic agents. There was a borderline difference between the mean (SD) calculated and measured HbA_1c levels (p = 0.054). There was a significant correlation between the calculated and measured HbA_1c (r = 0.595, p < 0.001). However, there was no agreement between the calculated and measured HbA_1c. The bias ±SD (limits of agreement) for calculated versus measured HbA_1c was −1.008 ± 2.02% (−5.05, 2.032).ConclusionDespite the presence of a significant correlation between the calculated and measured HbA_1c, the calculated level has shown an unacceptable agreement with the measured HbA_1c.