A mobile diabetes unit has been launched in the name of megastar Amitabh Bachchan, which will conduct free diabetes tests.

It was launched by the living legend himself on his 70th birthday, Thursday.

"Inaugurated 'Amitabh' the mobile diabetes unit from Silver Star, the noble charitable organisation that I patronise, in Mumbai...," Big B tweeted.

"Free diabetes tests conducted by these mobile units... proud to be associated with it in patron, and to contribute for its extension," he further posted.

Later in the day, Amitabh also inaugurated an exhibition of his 70 paintings and said he is overwhelmed by the gesture.

"And later an exhibition of 70 paintings by the most eminent artists of India, in remembrance of my birth and contribution...Just so overwhelming!!