ABSTRACT
BACKGROUND: It is well known that anemia and red cell turn over affects the HbA1c value. Iron deficiency anemia increases the HbA1c and haemolytic anemia lowers it. However, the cut-off of haemoglobin (Hb) or red-cell indices when the HbA1c value becomes unreliable is not known. AIM: We sought to find out values of HbA1c and red-cell indices where there is considerable discordance between HbA1c and plasma glucose (PG) values in the diagnosis of diabetes (DM) and pre-diabetes (Pre-DM) making HbA1c values unreliable. METHODS: A cross-sectional study of 237 non-diabetic subjects who attended our out-patient division of preventive health check-up clinics, between November 2016 and December 2017. Data was collected only from relatively healthy subjects who had voluntarily opted for undergoing a preventative health check-up (including a diabetes screening). Patients were classified as concordant (fasting and 2-hr post meal glucose values are in agreement with HbA1c) and discordant (values are not in agreement with HbA1c). RESULTS: A total of 237 patients (73% males) with mean age was 47.2±9.7 years (range 25-75) were included in the study. The HbA1c definition group had more diagnosis of DM (153 vs 96) and but lesser numbers of pre-DM (66 vs 102) compared to the PG group. Out of 237 patients, 133 (56%) showed concordance and 104 (44%) were discordant. The FPG, 2h-PPBG and HbA1c are significantly higher in the concordant group. The Hb value and MCV were significantly higher (p<0.05) in concordant group whereas, RDW and platelets are significantly higher (p<0.05) in discordant group. The highest rate of discordance was noted in the HbA1c strata of 6.5-7% (72%) followed by HbA1c of 5-6.4% (42%) and least in the HbA1c strata >7% (20%). While no single Hb or MCV value could predict discordance, a RDW value >17 was consistently associated with discordance across all the HbA1c strata. CONCLUSION: A HbA1c below 7% is significantly influenced by red-cell turn over indices and clinicians need to perform additional testing using plasma glucose levels to confirm the presence of diabetes or pre-diabetes. In patients whose RDW >17, HbA1c should be replaced by 75gm OGTT as a test of choice for diagnosis of diabetes or pre-diabetes.
ABSTRACT
Blood glucose monitoring has evolved over the last century. The concept of adequate glycemic control and minimum glycemic variability requires an ideal, accurate and reliable glucose monitoring system. The search for an ideal blood glucose monitoring system still continues. This review explains the various blood glucose monitoring systems with special focus on the monitoring systems like self- monitored blood glucose (SMBG) and continuous glucose monitoring system (CGMS). It also focuses on the newer concepts of blood glucose monitoring and their incorporation in routine clinical management of diabetes mellitus.
