Darkened skin on the groin is a sign of acanthosis nigricanis. This is a condition where there has been too much melanin production in a zone of the skin and subsequent darkening as well. This is a condition that occurs as a symptom of other conditions like hyperthyroidism, hypothyroidism, type 2 diabetes, acromegaly, and PCOD. The condition is nearly always associated with an underlying endocrinal disorder. It makes sense for you to visit an endocrinologist and have your hormone levels checked for insulin and thyroid hormones as well.
Diabetes is an autoimmune disease that is of two types. The first is called Type 1 diabetes and is caused when the body shuts down or kills of the insulin producing cells of the pancreas. Without insulin, the body cannot draw glucose from the blood for energy. Insulin’s fundamental role is to act like a switch between fuel sources. We normally use two sources of fuel – fat and sugar. When sugar levels are low, for example when we do not eat, the body will reduce the production of insulin. This is a prompt for the liver to start metabolizing fat from the adipose tissues effectively burning its stores and reserves of fat. This seems like a good strategy but there are some problems that occur. Fat has to be metabolized by the liver into ketones, but this production also causes the blood acidity levels to rise and this acidity will kill off other cells of the body and cause ketoacidosis to develop. This is usually a precursor to coma. In type 2 diabetes, the body is insulin resistant and this condition also causes the blood sugar levels to be too high. Ketoacidosis is a condition that can also occur in this type of diabetes, but the larger danger comes from the high sugar content osmotically pulling away water from the cells and dehydrating them. This very same mechanism also affects renal activity and causes kidney failure. The reasons for Type 2 diabetes developing are unclear and the finger of suspicion largely points towards genetics. Treating the condition requires you to change your diet to one that is less glucose based, and a typical diabetic’s diet of reduced consumption is needed.
The treatment for just the darkening of the areas of the groin would require that you make a vitamin C rich solution from squeezed lemons and onions. This preparation should be applied to the required areas and the results should be visible in a few weeks.