Darker fingerjoints. Teated please help!

I am getting concerned about my darker fingerjoint but not because of the skin color but due to underlying causes they might have my , is it normal for people with brown skin to have darker shades around joints or is it something else like diabetes , last year i had my hba1c fasting sugar and pp test all were normal , even at that time i had dark skin around it , yes i am overweight , but as far i remember i had them since young age my mother even has it but mu father dont , my mother also have high risk of diabetes as her both parents had diabetes and she recently got prediabetic , , is my dark skin die to diabetes or just normal hyperpigmentation , i am an big time hypochondriac please help , the thought of diabetes scare me out , do this means an early onset of disease also my vit b12 and d3 were low but i took medicine for that and d3 came normal and i am taking b12 for 3 months but yet to be teated please help