The interaction of stress and hormones
The stress hormone cortisol is constantly influencing our everyday life - even though we may not realize it. In every stressful situation our body secretes the hormone cortisol to activate a multitude of mechanisms. For our ancestors in the Stone Age this mechanism was very useful. They were also exposed to stress - but to stress of a different kind compared to today. When hunting predators, they had to decide to either Fight or Flight in order to survive. Seen symbolically, stress thus guaranteed everybody’s survival. Even though the relation to stress was completely different, everybody knows stress and everybody has already gotten through stressful times. According to the stress survey conducted by the German ‘Techniker Krankenkasse’ (a statutory health insurance company), 6 in 10 people state to feel stressed in everyday life. But what exactly happens in your body and which health consequences result from stress, especially if it is constantly taking up room in our lives?
In stressful situations, not only your psyche is affected. The hormone cortisol causes an interaction with various metabolic processes in your body. However, excessive stress can negatively influence your health so that the topic should become more important.
In the following you find more information on:
Why cortisol is associated with stress, how you can counteract the health consequences of stress and the importance of balanced cortisol levels for your stressful everyday life.
What is cortisol?
The stress hormone cortisol is a so-called steroid hormone and belongs to the group of glucocorticoids. When the body feels stress, more cortisol is secreted. Cortisol is produced by the adrenal cortex and has a wide variety of functions in the body. These include, among others, its influence on carbohydrate, protein and fat metabolism, blood pressure and blood sugar. Also in the immune system it plays an important role. 
What are glucocorticoids?
Glucocorticoids are steroid hormones which are produced in the adrenal cortex - mostly from cholesterol. The most important of these are cortisone and cortisol. They are centrally involved in increasing blood sugar levels, in immune response, in protein synthesis and the transformation of glucose into glycogen. 
What is Cortisone?
Cortisone is not the same as cortisol. It is the precursor of cortisol and it is the biochemically active form. [3, 4] Thus, the body’s cortisone doesn’t have an active function in human organism. In the current language, both chemical compounds have the same meaning which causes confusion.
Effects of cortisone in the body
In the pharmaceutical industry, cortisone has gained in popularity as it is produced synthetically and used, among others, in ointments for treating skin diseases as neurodermatitis. In therapeutic use, mostly preparations containing cortisone acetate are used. In the body, cortisone acetate is transformed into the active form cortisol.
Due to the anti-inflammatory effect of cortisol, cortisone is used for the treatment of various diseases. The drug is used to alleviate inflammatory processes when the cause of the disease is still unclear.
Cortisone is mainly used for diseases with increased risk of inflammation like rheumatism, arthritis, asthma, skin diseases and bronchitis. It is presented in various forms such as ointments, nasal sprays and injections.
Side-effects of cortisone
As soon as cortisone reaches the metabolism, it is transformed into cortisol. However, it can happen that more cortisol gets into the body than needed. This excess cortisol is accompanied by various side effects. These include, among others, increased susceptibility to infections, hyperglycaemia, high blood pressure, delayed wound healing and glaucoma. According to a study, it may cause growth disturbances in children.  The nature and intensity of the side effects depend on the dosage form and on the dose. Cortisone ointments and injections have only local effects whereas cortisone tablets have an effect on the whole body. 
Good to know:
In order to avoid confusion, you should know that the cortisone used in drugs is called hydrocortisone.
Hydrocortisone is used by doctors to treat skin diseases and joint inflammations.
Where is cortisol produced? A biochemical explanation
The production of cortisol takes place in one of the three regions of the adrenal cortex, in the so-called zona fasciculata. This process is activated by the hormone ACTH (adrenocorticotropic hormone). Cholesterol serves as a chemical precursor for its production. At first, cholesterol is transformed into pregnenolone. Then, it is either transformed into progesterone or 17α-hydroxypregnenolone. Finally, the stress hormone cortisol is produced from these. 
The adrenal glands
The adrenal glands are situated above the kidneys, weigh approx. 5 grams and are responsible for the production of several hormones. The comprise the adrenal glands and the adrenal medulla.
The adrenal cortex comprises three zones: 
- zona glomerulosa: production of aldosterone, responsible for the long-term regulation of blood pressure
- zona fasciculata: responsible for producing glucocorticoids
- zona reticularis: produces male and female sex hormones
A short overview: The adrenal glands comprise three zones. Cortisol is the most important glucocorticoid which is synthesized in the zona fasciculata. For the activation of this production, cholesterol and the peptide hormone adrenocorticotropic hormone (ACTH) are needed. ACTH is secreted by the pituitary and activates the production of glucocorticoids in the adrenal glands. When in a stressful situation, ACTH is released and the above-stated reactions are started. 
In the adrenal cortex, more precisely in the zona fasciculata, cholesterol is transformed into pregnenolone by means of the mitochondrial enzyme P450. Inside the endoplasmic reticulum, it is further transformed into progesterone or 17α-hydroxypregnenolone. In a final enzymatic reaction, the stress hormone cortisol is produced, which then pursues its many functions in the body. However, the transformation process can be impaired in case of disorders or diseases of the adrenal cortex. 
What are mitochondria, endoplasmic reticulum and enzymes?
Mitochondria: Mitochondria are the so-called powerhouses of the cells. They produce the universal energy source adenosine triphosphate (ATP) which is essential for nearly all metabolic processes of the body.
Endoplasmic reticulum: The endoplasmic reticulum is an organelle found in all human cells which produces and transports proteins.
Enzymes: Enzymes are proteins which are needed by the body to activate metabolic processes.
The role of cortisol in the body
Cortisol keeps us awake and alert. The function of cortisol, however, is much more widespread as it influences many metabolic processes:
- regulates carbohydrate, protein and lipid metabolism 
- increases blood sugar levels by transforming amino acids into glucose 
- inhibits inflammations by reducing the inflammatory factors 
- oppresses the immune system by reduced production of antibodies 
- supplies energy 
- releases insulin 
Cortisol is a hormone that is vital for the body. It participates in energy metabolism, maintenance of mineral metabolism and blood pressure, immune defence, stress processing, cell division and regulation of memory and brain function. 
Cortisol and its role in carbohydrate metabolism
Cortisol is especially important for carbohydrate supply due to its vital function. By releasing sugar in the form of glucose, cortisol increases blood sugar levels during the night when no food is consumed so that enough energy is available to the body. If the body produced no cortisol, this would result in nocturnal hypoglycaemia which in the worst case could lead to coma. 
Cortisol and its role in protein metabolism
Cortisol stimulates protein and lipid degradation for energy supply. Thus, the effect of cortisol is catabolic (degradative) as both fatty tissue and muscles are degraded. 
Cortisol and your immune system
The hormone Cortisol also influences your immune system. Administered in high doses, it has immunosuppressant effects. This means that your immune system and thus your immune defence are restricted. There are only low production levels of T-helper cells and B lymphocytes, which eliminate foreign bodies. Due to the reduced performance of the immune defence, susceptibility for infections increases. 
In medicine, however, this negative effect also has beneficial effects. Synthetically produced glucocorticoids such as prednisone are applied in autoimmune diseases, where the immune system attacks the body’s own healthy tissue. Due to its immunosuppressant effect, the immune system’s activity is reduced which avoids further damage. In addition, it is used in allergic reactions and chronic as well as acute inflammations. 
Cortisol and stress
From hereditary stress response to chronic stress
Stress alone, no matter for what reason, can increase cortisol levels. Therefore, it is also referred to as “stress hormone”. However, already in the Stone Age, this increase was vital. When hunting predators, our ancestors had to decide to either Fight or Flight in order to survive. In this situation, their body secreted cortisol which made them ready to either fight or flight. Adrenaline and cortisol flow into the body, blood pressure increases, breathing and pulse quicken and glucose is secreted for energy supply. Digestive and immune functions are stopped so that the body can focus on this new situation. The body provides all resources for either winning the fight or for enabling escape. Thus, our ancestors survived long enough to reproduce.
The balance of our metabolism and of our hormones is restored by the secretion of dopamine once the dangerous situation is over. Dopamine rewards our brains for mastering the challenge. 
What does ‘stress’ mean?
Everybody knows the term ‘stress’ and most people have already experienced stressful times. As per its definition, stress is the reaction of the human body to a stressful situation. The factor that causes the stress reaction is called stressor. A stressor can be any external stimulus or event which causes stress to an organism. Situations that are regarded as threatening or unpleasant can also be stressors. Disappointments, fears of failure and low self-confidence resp. low self-esteem are the most severe stressors. Stressors can be defined as stimuli, demands or obligations which have an impact on us. [12, 13]
Apart from stressors, also stress reactions and stress intensifiers are defined. The reaction to stress is different from person to person. Everyone reacts differently with individual physical and psychological behaviour. Intensifiers are personal motives, attitudes or assessments. They mediate between stressor and reaction and decide on the intensity of the reaction. 
Good to know:
According to the stress survey conducted by the German ‘Techniker Krankenkasse’ (a statutory health insurance company) in 2016, “6 in 10 Germans feel stressed - be it personal or in business. Almost one-fourth of the population, 23 percent, state to feel stressed very often.” 
Don’t worry - stressful times inevitably belong to our everyday lives and success involves overcoming obstacles. Even though it is not realistic to live and work in a stress-free world, humans are able to control what they perceive as stressful and how to react to this. 
Conclusion: We feel stressed when the demands of our environment exceed our coping strategies. Stress is a high psychic and mental strain by e.g. high workload or problems in family or partnership.
Today’s stress cascade
Nowadays, life is much more stressful than in the past and is laced with “Fight and Flight” situations - however, not with the objective of saving our lives. It is believed that today’s way of life lowers our bodie’s inhibition threshold to react the same way as our ancestors did and who needed the stress reaction for survival. This causes a permanent flow of stress hormones. The drawback to this development is that our balance can no longer be restored.  According to a study conducted by ‘The Physiological Society’, stress is a nationwide problem as there are only few regional differences. 
Cortisol - its role in stress
The term ‘stress’ has gained increasing popularity in recent years. According to a Forsa study, around 80 % of the 36- to 45-year-old suffer from stress, in school or at university, but also financial worries are hurting their lives. This stress experience is closely linked to complaints like headaches, back problems, neck tensions as well as gastrointestinal problems and can in the long run also encourage diseases. 
Cortisol is, apart from the so-called catecholamines noradrenaline, adrenaline and dopamine and their derivatives, the most important stress hormone. In stressful situations, cortisol production sharply increases. In general, the cortisol system responds slowly, other than the catecholamine system, which reacts immediately but eases soon. The stress reaction of the catecholamines causes the skin and intestinal vessels to constrict and the vessels in the muscles to expand. Furthermore, the redistribution of oxygen- and nutrient-rich blood for possible muscle effort is supported in case of the evolutionary “Fight and Flight”-response. This effect of catecholamines is only possible with the participation of cortisol. The hormones are regulated via the hormonal stress axis, the hypothalamic pituitary adrenal axis. The antagonist balances the hormone status as soon as variations occur. If this response mechanism in one of the organs is damaged or impaired due to permanent stress, the physiological cortisol levels derail. [17, 18]
What are catecholamines?
The main catecholamines are adrenaline, noradrenaline and dopamine. These three are the hormones for acute stress response. They are secreted when required and cause an increase of hormones in the body. Catecholamines have vital functions such as energy supply, securing respiration as well as cardiovascular functions - especially in case of chronic stress. 
How stress affects your health
Stress can affect your health. This is reported by the German ‘Techniker Krankenkasse’ (statutory health insurance company) in their most recent stress study. According to it, high and permanent stress affect physical and mental health. 30 % of the surveyed people who said that their health state was less well or even bad were suffering from permanent stress.  Here cortisol levels come into play.
Stress - especially permanent physical stress - can, for instance, negatively influence the mental performance and affect memory. This happens through long-term increase of cortisol levels. Normally, the brain perceives stress and releases the response at the very moment of physical or perceived threat. Cortisol is secreted due to several mechanisms. Cortisol guarantees the supply of physical resources for coping with the acute stress situation. These resources include energy reserves such as carbohydrates, lipids and proteins. 
Is stress a question of attitude?
Just over one fifth of people declare themselves to be very happy. The ratio is more than twice as high as for stressed people. With decreasing stress levels, the ratio of happy people rises. A major indicator is how you cope with stress. Techniques for stress coping and low cortisol levels can help to rebalance your individual stress levels 
Did you know that stress can also be good and positive?
The concentration of cortisol is subject to natural fluctuations which is typical of hormones. The concentration depends on the time of day. The following graphic shows you ideal cortisol levels throughout the day. Cortisol levels are highest in the morning between six and nine o’clock.  Hereby, the body is preparing for stressful situations during the day. In the course of the day, cortisol levels decrease and reach their low point around midnight. Cortisol is secreted in seven to ten peaks, therefore the concentration cannot be determined by just one single sample at only one point. 
Chronic stress leads to permanent activity of the stress axis. This means that cortisol production is increased not only in the morning but also during the night. After some time, the initially elevated cortisol night levels decrease but still exceed the normal value. The morning-evening-slope is maintained.
Under chronic stress, energy reserves are increasingly used and finally lead to an undersupply of the brain, which may cause symptoms. 
Under acute stress, the diurnal cortisol curve shows peaks in stress situations and then gets balanced, thus back to normal. The graphic ‘Example of a diurnal cortisol profile in various stress situations’ shows that the person has experienced a stressful situation 5 hours after the morning value. Afterwards, the level decreases back to the normal value. This is characteristic for acute stress.
The burnout syndrome is normally characterized by very low cortisol levels. There are several reasons for this. The (patho-)biological correlations have not finally been clarified in detail. Symptoms of burnout are, among others, lack of drive, impaired concentration, fatigue, gastrointestinal disorders, insomnia, lack of motivation, cynicism and reduced performance. Apart from the consequences of these symptoms for our private and professional lives, it may lead to depression. For these reasons it is important to take changed cortisol levels seriously and consult a therapist.
Good to know:
A recent study in Switzerland reportea severe burnout in 4 % and a moderately severe burnout in nearly one third of study participants. This corresponds to the European average. 
What causes cortisol deficiency?
A lack of free cortisol in the body has mainly organic causes. In case of adrenal insufficiency (= underactivity of the adrenal cortex) cortisol levels are low due to deficient production. This disease condition is called Addison’s disease. Apart from insufficiency, adrenal fatigue due to overstressing is being discussed as another cause. In addition to organic causes, the burnout syndrome can encourage cortisol deficiency.
Addison’s disease is a chronic disorder of the adrenal cortex which leads to insufficiency. This autoimmune reaction of the body against the adrenal cortex is the most common cause. As a result, no or too few glucocorticoids are produced. Particularly affected are women aged 20 to 40 years old. If Addison’s disease is not treated, the condition can develop up to an Addisonian crisis which is life-threatening. 
There are different explanations for depressed cortisol levels in burnout syndrome. However, the connections causing this disease have not finally been clarified. For these reasons it is important to take changed cortisol levels seriously and consult a therapist.
What are symptoms of cortisol deficiency?
Symptoms of cortisol deficiency may be: 
low blood pressure and salt craving
fatigue and feeling of faintness
gastrointestinal disorders such as lack of appetite, vomiting, nausea, stomach pains
muscle pains and muscle weakness
depression and irritability
dark skin pigmentation
hair loss and libido problems (esp. women)
On the basis of these symptoms either cortisol deficiency or Addison’s disease can be suspected. For diagnostic clarification you should consult a doctor.
Conclusion: The symptoms of cortisol deficiency make clear that cortisol has various functions in the body. The deficiency affects psyche, skin and hair, muscles, gastrointestinal tract, heart and even sex life. 
High Cortisol levels
What causes excess cortisol levels?
High cortisol levels in the morning are usually normal - as long as they remain within a certain range. Should, however, high cortisol levels occur throughout the day, this may be caused by [8, 17, 24]:
- Cushing’s disease
- birth control pills, drugs containing glucocorticoids
- overweight or anorexia
- burn injuries
Cushing’s disease is correlating with increased cortisol levels. These can be caused by a too high dosage of drugs containing glucocorticoids or by tumours which produce more adrenocorticotropic hormone (ACTH). ACTH stimulates the adrenal cortex to produce cortisol. As soon as ACTH is released in excess, the cortisol synthesis increases drastically. This results in several disorders which are caused by excess cortisol. 
Permanent stress and depressions are also main causes for too high cortisol levels. In stressful situations, normally an appropriate amount of cortisol is secreted to set the body to ‘survival mode’. If you suffer from stress more often and especially in case of high stress, too much cortisol is produced. [10, 18]
Due to certain life circumstances, such as pregnancy and in case of alcoholism, the so-called Pseudo-Cushing’s syndrome can occur. In this syndrome, the elevated values do not result from organic conditions. Overweight, infections, anorexia, acute psychosis, intake of birth control pills or burn injuries can also increase cortisol levels. [18, 25]
What are symptoms of high cortisol levels?
High cortisol levels can affect wound healing and the incorporation of nutrients into the bones. This increases the risk of developing osteoporosis (bone loss) which may result in bone pains and fractures. Several studies also found a correlation between elevated cortisol levels and depressions. Increased cortisol secretion leads to reduced fat burning with the effect of weight gain. Moreover, skin changes, high blood pressure and high blood sugar values can result from this. 
Cushing’s disease is also associated with the following symptoms:
- moon face
- buffalo hump
- weight gain with truncal obesity (abdomen, neck, face)
- increase in blood pressure
- disturbances of the carbohydrate metabolism (impaired glucose tolerance / diabetes mellitus)
- osteoporosis due to reduced calcium absorption and reduced bone renewal
- muscle weakness
- thin extremities due to muscle atrophy
- thinning, fragile skin that bruises easily
- easy bruising
- hair loss
In women, elevated cortisol levels can also lead to thicker or more visible body and facial hair (hirsutism), irregular or absent menstrual periods and in men to impotence and loss of libido and fertility. 
What are treatments for low cortisol?
When the test result shows low cortisol levels, it is necessary to find out the underlying cause. Cortisol deficiency is mostly caused by diseases of the adrenal cortex such as Addison’s disease and adrenal fatigue (adrenal insufficiency). In order to rebalance cortisol levels, the active substance hydrocortisone is used. It may also be caused by burnout syndrome.
Addison’s disease is a chronic condition. Therefore, the function of the adrenal cortex must lifelong be guaranteed by drugs. Hydrocortisone assumes the function of cortisol in the body. In addition, further drugs have to be taken to replace the other glucocorticoids and to ensure the production of hormones. In order to avoid an Addisonian crisis, which can lead to fainting, every patient should carry an emergency card. This document contains actions required in case of fainting. The crisis must be treated promptly by administration of glucocorticoid drugs!
The therapy of burnout syndromes involves psychological treatment. The psychologist or psychiatrist helps the patient to find a way out of permanent stress load. Moreover, the patients are prescribed antidepressants. If medication is not suitable, the patient can learn stress management techniques in order to better cope with stress in daily life.
What are treatments for high cortisol?
High cortisol levels can have various causes such as diseases, lifestyle and drugs. Therefore, therapy needs to be adapted to the respective cause of increased cortisol levels. Diseases such as Cushing’s disease, in which more cortisol is produced due to a tumour, must be treated by either drugs or by an operation. For therapy of depressions, mostly antidepressants are prescribed. However, if causes are non-organic, these could also be treated without drugs! [8, 18, 25]
How to lower cortisol levels naturally
Apart from successful therapy or cure of the underlying disease, which help to normalize stress regulation, there are further ways to rebalance cortisol levels - completely without drugs.  Please read on for information on how to lower blood levels as well as simple and effective tips: 
- Give your body the chance to regenerate! Sufficient high-quality sleep helps to reduce stress.
- Do sports! Sport helps to relieve stress and can normalize cortisol levels.
- Allow time for relaxation! For example, use stress management techniques.
- Ensure to take time for intimacy and social contacts on a regular basis! Hereby you activate the “feel-good” hormone oxytocin. It is released as a result of physical contact and social support and lets your cortisol levels recover.
How to lower cortisol levels by your diet
Your diet alone can work wonders for fighting elevated but also too low cortisol levels. In the following, we have listed some nutritional advice with effects on cortisol levels, which is even scientifically proven:
Take vitamin B!
Vitamin B complex, especially B6 and folic acid, help to reduce work stress and improve your mood. Legumes, fish, walnuts, yeast and soy are rich in these vitamins. 
Reduce coffee consumption!
Coffee increases the cortisol level. 
Drink black tea!
Black tea lowers your cortisol levels. However, please only drink tea if it is not contradicted by serious health reasons. 
Eat dark chocolate!
It doesn’t only contain antioxidants, but also reduces cortisol levels. 
It is rich in omega-3 fatty acids which reduce the release of cortisol. Prefer mackerel, herring and salmon. Some vegetable oils like rapeseed oil and soybean oil also contain larger amounts of omega-3 fatty acids. 
It reduces the cortisol secretion. Oysters contain lots of zinc. Edam and Emmental cheese as well as chicken eggs are also ideal sources. 
Vitamin C helps!
Peppers, citrus fruits and berries are rich in vitamin C. It helps to normalize cortisol levels. Eat them fresh, as vitamin C is unstable and is easily destroyed by heating and exposure to sunlight. In case of low cortisol-levels which are not caused by burnout syndrome, grapefruits help to raise cortisol blood levels. 
To all liquorice lovers!
Liquorice and one of its ingredients, glycyrrhetic acid, can also increase cortisol levels. Pregnant women, however, should refrain from eating liquorice as the embryo cannot counter this influence. People who take anticoagulants should only eat liquorice in smaller quantities or better avoid it as it contains vitamin K. 
Cortisol and dark chocolate
Dark chocolate - the perfect snack for stress relief
Eating chocolate makes us happy and is a ‘rescuer’ is stressful times - this is a fact for many people. In a recent study, scientists could prove a slower increase of cortisol levels. 
It is assumed that the flavonoids contained in dark chocolate, which belong to the antioxidants, inhibit the secretion of cortisol and adrenaline.
Good to know:
Antioxidants are known for their radical scavenging activities. Due to their chemical bond, they can slow down or even stop oxidation of other substances. Antioxidants occur in nature, but due to their positive health effects, they are increasingly synthetically made. The most well known antioxidants are vitamin C, vitamin E, micronutrients such as zinc and selenium, carotenoids and beta-carotene. 
In 2014, a study investigated the effects of dark chocolate on cortisol-levels. One half of study participants ate half a bar of chocolate and the other half, the so-called placebo group, ate chocolate without flavonoids. Afterwards, they all had to pass a stress test. 
Result: In the persons that ate dark chocolate, the levels of the stress hormones cortisol and adrenaline rose slower. The higher flavonoid blood levels, the smaller the increase of stress hormones. 
Conclusion: Dark chocolate can reduce secretion of stress hormones due to the flavonoids contained.
How to lower cortisol levels by stress management techniques
Dealing with stress is not inherited. For some, drinking a cup of tea and reading a book already helps to come to rest. For others, a punching bag or other sports help to relax. All of these have in common that they improve subjective stress perception but they don’t tackle the problem at source to reduce cortisol levels in the long run.
Professional stress management classes can be a good start for effective and lasting stress management. Skilled trainers can show you which are your individual triggers (stressors) and which practical tips and tricks help you balance your stress hormones. 
There is a wide range of stress management classes and techniques and the offer is confusing. As the correlation of stress and cortisol and their impact on health are well-known, there is a wide variety of preventative courses. Please check with your health insurance company whether they cover the course fees.
How to lower cortisol levels through medication
Medication is only used if cortisol is needed lifelong and no other therapy can help like e.g. in Addison’s disease or Cushing syndrome. For a long time, the drugs metyrapone, aminoglutehimide, mifepriston and ketoconazole have been used. They lower cortisol levels by inhibiting the enzyme needed for the synthesis of steroids. [37, 38]
How to get your cortisol levels under control?A visit to the doctor is the traditional way of being tested. However, this involves long waiting periods which causes stress to the patient and therefore, results may be distorted. In order to save the waiting time, an alternative was developed, the cortisol self-test Depending on the time of day, cortisol levels are subject to considerable fluctuations: between 6 and 8 o’clock in the morning, they are highest and around midnight lowest. You can find the reference values in the following graphic.
Measuring cortisol is simple. By means of the cerascreen® Cortisol Test you can test your cortisol levels from home. The self-test creates a day profile which illustrates the times when cortisol-levels are high (i.e. when your stress is highest). For the analysis, seven saliva samples are needed which have to be taken within 12 hours. As the values fluctuate during the morning, one ‘mean value’ of the first three samples is determined. This ‘mean value’ is then showing the ‘morning value’.
Good to know:
The majority of cortisol in the blood is (protein-)bound. Approx. one to three percent are free. Only the free form is the active form. It is secreted into saliva and can be measured in it. As cortisol levels change under stress, sample taking of saliva at home is the most stress-free way of analysis. [39, 40]
Cortisol and diabetes
Diabetes mellitus is a blood sugar disease. The insulin production is impaired an leads to fluctuations in blood sugar levels. 
Under stress, cortisol levels rise and lead to increased sugar secretion. Blood sugar levels rise.  This causes increased secretion of insulin by the pancreas. If the pancreas has to permanently struggle against elevated blood sugar levels, this can lead to diabetes in the long run. Due to the excess supply with insulin, the receptors that process insulin react less and less sensitive to it. This can lead to insulin resistance and diabetes mellitus type 2. 
Conclusion: The secretion of cortisol under stress entails elevated blood sugar values. To lower these, insulin is secreted. Permanent and long-lasting secretion of cortisol can lead to insulin resistance. This causes diabetes mellitus type 2.
Cortisol and overweight
A large-scale study with 160,000 professionals revealed the correlation between elevated cortisol levels and overweight.  However, the current study situation is still very contradictory.
It is assumed that increased cortisol levels lead to changes in the fat cells. The mature fat cells (adipocytes) are produced from their precursors, the preadipocytes. In contrast to the preadipocytes, the adipocytes store fat. This can lead to weight gain. 
Conclusion: Whether overweight is really directly correlating with changed cortisol values could not yet be scientifically validated. It is only assumed that changes in the fat cells result from elevated cortisol levels in the body.
Cortisol and depression
In Britain, 19 % of people state to be depressed according to a survey conducted by the National Centre of Social Research with 5,000 adults. 
According to an article in the ‘Pharmazeutische Zeitung’ (German pharmaceutical trade journal), people with depressions have elevated cortisol levels. It is assumed that this is caused by a physiological dysfunction which suppresses hormones which normally avoid high cortisol levels. 
Is depression a stress disorder?
More and more results indicate that depression is a stress disorder. In fact, there is a correlation. Thus, impaired regulation of stress hormones is assumed to contribute to the development and course of a depression.
An epidemiologic study associated early negative social factors with the increased risk to develop depression. These factors include natural disasters, neglect, physical violence or sexual abuse. Changes in one’s personal environment are another risk factor triggering depressive episodes. Negative events can also be causes. Cortisol is coming into play as soon as there are stressful situations and adaptions of bodies. The hormone and the resulting mechanisms lead to a reregulation once the adaption has taken place. If one of the finely tuned processes is faulty, for example due to chronic stress, various disorders can result and as can depression. 
Depressions resulting from chronic stress in particular increase the risk to develop cardiovascular diseases. How this relates has not yet been clarified. A working group of an Ulm-based hospital recently came across a possible explanation. A study showed that the stress hormone cortisol seems to play an important role in this context. The study participants had to undergo a stress test. 
Result: A blood analysis of the study participants showed that cortisol levels were highest in depressed people without cardiovascular diseases.
Depressions are assumed to correlate with the secretion of the stress hormone cortisol. Excess cortisol can in the long run lead to fat deposits in the blood vessels and thus lead to arteriosclerosis. For this reason, depressed people have an increased risk of developing cardiovascular diseases.
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