U r suffering from premature ejaculation
Factor causing this in diabetic patient is prolonged uncontrolled sugar level.
If ur sugar level is normal then give attention to following factors:
1.Timing of act: choose one when u r less tired one specialy morning one
2.Position of act: choose one which is less straining to ur thighs
3.Spend more time with ur partner in foreplay,dont be in hurry in insertion
4.Use Stop & Squeeze technique i.e. when u have urge to ejaculate stop thirsting and squeeze glans
of ur penis till urge goes and start thirsting again...continue this till u get orgasm.
If this doesnt help consult psychiatrist
who can guide u and can prescribe appropriate medicine.