It is my understanding that the adrenal fatigue comes first. The adrenals pump out cortisol, which helps us deal with stress. The adrenals also play a role in gluconeogenesis (making of new glucose) by releasing glucagon (which works the opposite of insulin). When the adrenals are over worked because of periods of chronic, intense stress, they are unable to work efficiently. This means that the process of gluconeogenesis is impeded, causing one to have low blood sugar.