BACKGROUNDThe aim of the study is to examine endothelial dysfunction in type 2 diabetes with inadequate glycaemic control and to study improvement in endothelial function after glycaemic control. MATERIALS AND METHODSAn observational study was performed in type 2 diabetic patients (35-60 years) with inadequate glycaemic control. Endothelial function was evaluated by non-invasive method. Flow associated dilation (%FAD) change in lumen diameter of brachial artery after glyceryl trinitrate spray (%GTN) were calculated. After achieving glycaemic control for >3 months, HbA1c and endothelial function test were compared with baseline. RESULTSOut of 73 patients (mean age 50.79±4.96 years) enrolled, 46.5% were male and 41.09% were overweight. The mean duration of diabetes was 4.84 ± 3.2 years. Significant difference was noted in HbA1c, fasting blood glucose and postprandial blood glucose after treatment (p<0.05 for all). Mean %FAD before glycaemic control was 7.34 ± 2.16 whereas mean % GTN was 14.60 ± 2.96; 89% patients had % FAD <10%. Significant improvement was observed in %FAD after glycaemic control (p<0.05) but not in %GTN (p=0.47). Percentage FAD significantly increased after glycaemic control in patients with HbA1c <7% (p<0.05). No significant difference was seen in % GTN in patients with HbA1c less than or more than 7% (p>0.05). %FAD did not improve in patients with baseline HbA1c >7% (p>0.05). After anti-diabetic therapy, reduction in HbA1c (p <0.05) and %improvement in FAD (p< 0.01) was better in patients with baseline HbA1c <7% compared to those with >7%. HbA1c and body mass index had significantly negative correlation with %FAD before as well as after glycaemic control. CONCLUSIONUncontrolled type 2 diabetes mellitus is associated with impaired endothelial function. Negative correlation is observed between endothelial dysfunction and glycaemic status of type 2 diabetes patients. Glycaemic control results in improvement of endothelial dysfunction.