Background: Glycated hemoglobin is a well established marker used extensively to monitor long term (3 monthly) glycemic control in diabetic patients. Apart from blood sugar, HbA1c levels are also affected by the presence of variant hemoglobins, hemolytic anemias, nutritional anemias, uremia, pregnancy, and acute blood loss. In the recent past, there have been several studies reporting negative as well as positive association between HbA1c and Hb levels. 

Aims: to study the association of hemoglobin with glycated hemoglobin levels in type 2 diabetic subjects
Methods: Data was collected from 3090 type 2 diabetic patients attending diabetic clinic of the institute from  April 2011 to March 2015.  Anthropometry, detailed history and clinical examination, fasting and 2hr post-prandial plasma glucose, hemoglobin, glycated hemoglobin, lipid profile and LFT, KFT were done in all the patients. Analysis was done using IBM SPSS 23.
Results: Mean age of the study subjects was 50.71±10.60 yrs, FPG was 178.83±70.50 and PPPG was 250.22  ± 101.47.  The mean Hb was 12.60±3.78  and HbA1c was 9.39± 2.42. HbA1c levels correlated positively with Hb (r=0.072, P<0.001). Significant positive correlation was also found in females as well as male patients separately. Though the correlation between HbA1c and Hb was stronger in female patients (r= 0.12, P<0.001) than male patients (r= 0.056, P<0.049).  Further, stepwise multiple regression analysis showed that Hb independently affects HbA1c levels in females (adjusted R squared= 0.34) as well as males (adjusted R squared= 0.25).
Conclusion: There is a positive correlation between Hb and HbA1c levels in type 2 diabetic patients. Further Hb was found to be an independent factor affecting HBA1c levels in both the sexes.

Association of hemoglobin with glycated hemoglobin in type 2 diabetic patients