Pregnant in 6 weeks and no heart beeb? blood sugar 210, weight 105 kg, 31 yrs. when heart beeb start & when to worry ?

Depends: A vaginal ultrasound can usually show a beating heart by week 6 of a pregnancy (dated accurately), but an ultrasound on the belly often won't see it until week 7 or so depending on machine quality and skill of the ultrasonographer. If you're trying to listen with a little Doppler (sound only, no picture), you can't expect to hear a beat until week 12 even if you're good.