Objective: To determine median HbA1c level in patients screened for DM and compare the diagnostic accuracy of HbA1c with the currently recommended ADA cut off, using 2 hours (h) plasma glucose (2-h PG) post 75 grams oral glucose tolerance test (OGTT) as gold standard.
Study Design: Cross sectional study.
Place and Duration of Study: Aga Khan University Hospital Karachi, from Jul 2014 to Nov 2015.
Patients and Methods: Consecutive subjects screened by OGTT for diabetes mellitus (DM) were included. Blood sample for plasma glucose and HbA1c were analyzed on ADVIA 1800.
Results: Total 146 subjects were included with median age 45 (IQR 54.2-35) years; 53% (n=77) being females. Median HbA1c of the study subjects was 6% (IQR 6.6-5.6). Positive correlation was observed between age and HbA1c [5.7% (IQR 6.2-5.3) <40 y, 6.2% (IQR 6.8-5.8) in >40 y subjects; r 0.34, p=0.000). Males had higher HbA1c than females [6.1% (IQR 6.8-5.7) years. 5.9% (IQR 6.4-5.4); r 0.17, p=0.036). HbA1c levels were significantly different amongst the different ethnic groups residing in Pakistan (p-value<0.03). HbA1c was positively correlated with FPG (r=0.59, p-value<0.001) and 2-h PG (r=0.56, p-value<0.001). Sensitivity, specificity, PPV, NPV for HbA1c at cutoff of 6.5% in diagnosing diabetes mellitus (DM) were 70%, 89%, 72% and 80% respectively.
Conclusion: High median HbA1c levels is noted in our subjects. At cut off level of HbA1c ≥6.5%, 70% of subjects with DM were diagnosed using ADA criteria of 2-h PG for diabetes as gold standard. Ethnic differences were also observed in levels of HbA1c. There is a need to define cut off for our population.
Keywords : Diabetes Mellitus, Ethnic Groups, Glycosylated Hemoglobin (HbA1c).