Need Solution for RingFinger problem?

I am a recently diagnosed diabetic of 40 years old with controlled blood sugar (150) average. My ring finger on both hands are not able to fold fully for the past 9 months(precisely). I maintain regular weight exercise for the last 15 years with strong physique. My favourite is Bench Press with heavy weight 90— 100 kgs. During lifting weights am able to fold the fingers to some extent but during night my ring fingers gets freezed. I stopped exercising one week to see the result,but still it persists. Need help to know why it is happening for long months. I haven’t took any medicine or treatment yet, except stretching myself with a hope to get to normal soon. Would like to know will it get cured and what is disease called ?