Diabetes mellitus
This information excludes diabetic emergencies which are covered in the non-infective emergency hand-out.
Diabetes mellitus definition
This is a disease characterised by lack of or ineffective utilisation of the body’s insulin.
This disease leaves patients with high blood sugars.
Symptoms
Patients typically complain of thirst, polydipsia (drinking lots), polyuria (passing lots of urine), lethargy and increased incidence of infections.
Patients can however present very differently with no symptoms at all or with severe illness caused by one of the diabetic emergencies.
If there is any doubt the blood sugar is easily checked with a glucose machine (this should be done in any unwell or worrying patients)
Diagnosing diabetes
A random blood sugar above 11mmol/L (200mg/dL) in the presence of correct symptoms is virtually diagnostic of diabetes but it needs to be confirmed by a fasting glucose of above 7 mmol/L(126mg/dL).
Other methods not used as much in Malawi involve measuring HbA1c which measures how much glucose has been in the blood over the past 8 weeks and above 7% is also diagnostic.
Someone presenting in diabetic ketoacidosis (high blood sugar and ketones + in the urine) or hyperosmolar non-ketotic coma is also diagnosed as diabetic.
Types 1 vs 2
There are two types of diabetes:
· In type 1 diabetes the Beta cells of the pancreas which produce insulin are destroyed by an autoimmune process, these patients have no insulin
· In type 2 diabetes the patient’s body has reduced sensitivity to the insulin they produce, these patients produce insulin but it doesn’t work as well
Type 1 diabetics present differently and are treated differently to type 2 diabetics.
Type 1
These patients tend to be young (less then 30 years), they tend to present fairly quickly with symptoms coming on in sometimes less than a week. They have high blood sugars, pass great volumes of water and lose weight.
These patients also can develop diabetic ketoacidosis if they do not receive insulin in prolonged periods of time.
Managing type 1 diabetics
Lifestyle
All diabetics should be advised to take regular exercise to avoid sugary or fatty foods with vegetables making up the majority of their diet.(see picture of the ideal ratios of foods)
All type 1 diabetics need insulin as they have non. This is present mainly in two forms in Malawi…
· Soluble which lasts for around two hours
· Lente which lasts for around twelve hours.
When someone is diagnosed with type one diabetes they are started on insulin via the rule of thirds.
Insulin rule of thirds
To do this take the patients weight in kg and times it by 0.5 to 1.0, this will give you the total volume of insulin needed in units.
Take this total number and split it into two thirds and one third. The two thirds is the total volume of lente the one third is the total volume of soluble.
The total volume of each of these is then split into two thirds which is given in the morning and one third which is given at the evening meal.
Example a 60 kg man to start insulin
60 x 0.5 = 30 units of insulin total
30 x 2/3 = 20 units lente total to be given
20 x 2/3 = 13 units given in the morning
20 x 1/3= 7 units given with the evening meal
30x 1/3= 10 units soluble total
10 x 2/3= 7 units given in the morning
10 x 1/3= 3 units given in the evening
This man can be started on 20 units lente and 7 units soluble in the morning whilst in with his evening meal he will take 7 units of lente and 3 units of soluble.
This dose is reviewed after starting to see if the regime needs increasing or decreasing.
Type 2 diabetics
These patients tend to be over 30 years of age and obese. The patent will ften present with mild symptoms or be a symptomatic and picked up when testing blood sugars.
Treatment of type 2 diabetes
The first stage of treatment is lifestyle measures. Reducing weight and sugar intake can dramatically reduce and even cure type 2 diabetes in some instances. In the majority of instances the patient will be unable to lose the weight and will need medications.
Type 2 diabetics can be first treated with oral medications; there are two tablets available in Malawi:
Metformin given at a dose of 500mg BD to 2g TDS, this increases the body’s sensitivity to insulin. It is the first line medication in type 2 diabetes. It can occasionally cause lactic acidosis and should be stopped immediately if muscle cramps develop.
Glibenclamide is given at a dose of 5 mg OD to 10 mg BD, this tablet increases the body’s secretion of insulin. It is more likely to cause hypoglycaemia than metformin and causes weight gain.
A patient is started on metformin and then the dose is increased and glibenclamide is added to control the blood sugar. If this is ineffective and the blood sugar is still high a once daily dose of lente is added at 0.3 units per kg. if control is still not achieved then all diabetic medications are stopped and the patient is started on insulin via the rule of thirds as detailed above.
Long term complications
Diabetes will cause a great deal of long term complications in a patient the main complications are grouped as follows…
· Neurological problems
· Vascular problems
· Kidney problems
· Eye problems
· Impotence
· Diabetic foot
Neurological problems
Diabetes can cause a wide spectrum of neurological complications:
Ø Peripheral Neuropathy
Ø Radiculopathies
Ø Mono-neuropathies
Ø Autonomic neuropathies
Peripheral neuropathy
Is one of the commonest complications seen when reviewing long term diabetic patients. The patients present with numbness or tingling of the feet as the nerves at the periphery are destroyed. It is said to take a ‘glove and stocking’ distribution as it progresses and these areas become numb. You will find the patient has decreased sensation from the tips of their feet extending upwards possibly even behind their knees.
There is no direct treatment to reverse peripheral neuropathy and it is likely the problem will steadily worsen and the numbness will spread up the legs.
The tingling and burning sensation can be treated with amitriptyline 25mg nocte, whislt pyridoxine is often given to replace any vitamins which may be contributing to the numbness.
Other causes of common causes of peripheral neuropathy are alcohol, B12 anaemia and vitamin deficiency. These need to be excluded and treated.
Radiculopathies
This presents as an aching often in the back in the pattern that is the same as is seen in herpes zoster infection. This is a tingling or burning pain in the skin following a band pattern from the back to the centre of the abdomen chest. It is treated with amitriptyline 25mg nocte.
Mono-neuropathies
Diabetic patients can have a weakness develop spontaneously in any of their nerves. Common sites include the 3rd and 6th cranial nerves and the radial nerve causing a wrist drop.
Autonomic neuropathies
These nerves are responsible for peristalsis, increasing BP when standing up and maintaining erection. Symptoms of damage to these nerves tend to be gastrointestinal with stomach cramps, vomiting, bloating and diarrhoea. Postural hypotension causes dizziness when standing up and the patient is often impotent.
There is no direct treatment, laxatives or constipating drugs may be appropriate.
Vascular complications
Diabetes increases the incidence of all vascular diseases these include:
Ø Strokes
Ø Heart disease (heart attacks, angina)
Ø Peripheral vascular disease
Ø Impotence
This is because the increased blood sugar act like a rust in the blood vessels and increase the rate of damage.
These diseases are treated in the same manner as non-diabetic patients with increased emphasis on blood sugar control.
Kidney Problems
These are caused as part of the vascular disease. Poor blood supply to the kidneys and damage to the small vessels in the kidneys is due to the higher levels of the blood sugar in the preceding years.
This results in a faster rate of developing chronic kidney disease.
Kidney disease is looked for in the U+E and urinalysis showing protein or microalbuminuria. The rate of kidney disease is decreased using captopril to control the blood pressure starting at 12.5 mg BD and titrating upwards. If this does not control BP then other drugs can be added as per the BP protocol. HCT is not used until all other anti-hypertensive options have been added as it can increase the blood sugar further.
Retinopathy
The increased blood sugar levels over time cause damage to the small vessels at the back of the eye. This can cause microaneurysms (dots), small haemorrhages (blots) and new vessel formation on the retina. This can be treated with laser therapy to reduce the hypoxia of the retina and preserve the central vision.
Impotence
Male diabetics are at increased risk of impotence due to vascular disease and autonomic neuropathy the patient will struggle to form a strong erection or maintain and erection for the duration of intercourse.
This can be treated with Viagra or Cialis if the patient is able to buy them himself.
Diabetic foot
This is again a result of neuropathy and vascular disease as patients are unable to feel the feet and so do not protect them and the feet do not heal as well as the blood supply to them is compromised. An increased blood sugar also creates favourable conditions for bacteria to grow which if complicating will worsening all wounds.
Foot ulcers tend to progress more rapidly and are slower to heal. Joints in the foot can also become malformed as the patient doesn’t feel the bone destruction due to autonomic neuropathy.
Reviewing a diabetic patient in Clinic
The following should be checked in all diabetic patients attending clinic
Ø Blood sugar (fasting) target is less than 6.7 mmol/L (120mg/dL)
Ø BP target is below 130/80 mmHg
Ø Weight (is it increasing)
Ø Feet (are they kept clean)
Ø Eyes (is the vision ok?)
Ø Urine and U+E are recommended to be checked yearly
Interpreting blood sugar results
Blood sugar indicates the diabetic control; a high blood sugar could be due to a number of reasons. Increased blood sugar may be due to inadequate diabetic control from the medications to decide this you must firstly establish what medication the individual is on and when did they last take it. It is not uncommon for diabetic patients to run out of medications before they come to clinic or the pharmacy has run out of stock and they were unable to afford them.
If the patient has not taken their medication for more than the past day the effectiveness of the drugs cannot be judged and it may be wise to re-prescribe the old regime and check again in two weeks.
If the compliance is good then check the patient was fasting when the sample was taken.
HbA1c indicates control over the last 8 weeks and will tell you if the drug regime is working (should be lower than 7%). If not you may need to increase the diabetic drugs.
Increasing diabetic drugs
Once you have decided the drugs are not working effectively to reduce blood sugar then you must increase the medications. There is no set rule on specific doses to increase diabetic drugs and patients will not respond in a standard way. A cautious approach to increasing the doses should be used.
Increasing insulin is usually done by adding extra units to each dose in the same ratio as the rule of thirds.
Example
A Type 1 diabetic presents to clinic with a fasting blood sugar of 17mmol/L (300mg/dl). He is on insulin:
} Lente 20 units am and 10 units pm
} Soluble 10 units am and 5 units pm
What is your action?
Answer :
I would check compliance and that he had fasted when the sample was taken. I would ensure his blood pressure weight, feet and eyes were checked.
If his compliance is good and he had fasted I would increase his insulin by 8 units total to
} Lente 24 units am and 12 units pm
} Soluble 12 units am and 6 units pm
I would advise correct diabetic diet and exercise and esure his U+E and urine were checked in the last year.
I would also tell him about the symptoms of hypo’s and ask him to come back if he had any symptoms and reduce his insulin.
Blood Sugar Measurement Conversion
To convert mmol/L to mg/dL times by 18.
mmol/L mg/dL
2.8 50
3.1 55
4 70
6.1 110
10 180
13.9 250
33.3 600
66.6 1200
Provided by T. Whitfield 2012