In Morocco, according to WHO estimates, the prevalence rate of diabetes in the adult population is 12.4%. This pathology is the cause of more than 12,000 deaths per year. Glycemic control prevents the progression of most complications. Currently, glycated hemoglobin (HbA1c) is the most relevant biological marker for monitoring diabetic patients. The objective of this work is to study the correlation between HbA1c and fasting blood sugar (G0) in diabetic patients at the CHI Ibn Rochd in Casablanca. Fasting blood glucose was sampled on a dry tube and analyzed on the Alinity ® Abbott automaton by an enzymatic method using Hexokinase. The HbA1c assay, taken on tri-potassium EDTA, was carried out by High Performance Liquid Chromatography (HPLC) on an ADAMS TM A1c HA-8180v automaton. Statistical analysis was performed using SPSS software. The correlation between HbA1c and G0 was positive with the Pearson correlation coefficient at r=0.69 and P < 0.001. A 1% rise in the HbA1c value would correspond approximately to a 0.69 g/l rise for the G0 found from the regression curve equation: HbA1C= 4.680 + 1.458 x G0. Our study found a good correlation between fasting blood glucose and HbA1c in Moroccan diabetic adults, which could be useful in clinical practice for better control of glycemic balance.