Diabetes mellitus is a common disorder characterised by persistently high blood glucose levels. It is due to multiple genetic and environmental factors, which result in defects in the action or secretion of insulin thereby causing a disturbance in the metabolism of carbohydrates, fat and protein. Many individuals with diabetes do not complain of symptoms. There is therefore the need to screen all patients (including pregnant women) attending health facilities to exclude diabetes.
A diagnosis of diabetes is suggested when the fasting whole blood glucose level is 6.1 mmol/L or more and/or random blood glucose, taken 2 hours after a meal or 75 g glucose load (1.75 g/kg body weight in children) is 10.0 mmol/L or more.
COMMON CAUSES
Three common forms of diabetes are encountered in practice:
• Type 1 diabetes - (formerly called insulin-dependent diabetes mellitus)
• Type 2 diabetes - (formerly called non-insulin-dependent diabetes mellitus)
• Gestational Diabetes (diabetes developing during pregnancy in previously non-diabetic individuals). See section on Diabetes in Pregnancy
SYMPTOMS
Many patients with diabetes do not have symptoms. Their diabetes is only detected on screening tests. Patients presenting with symptoms may have the following:
• Polyuria - passage of large amounts of urine
• Thirst and excessive drinking of water
• Unexplained weight loss
• Blurred vision
• Recurrent boils
• Pruritus vulvae
• Complications of diabetes (e.g. foot gangrene, poor vision, stroke, heart attack, impotence, infertility, large babies, recurrent still births, miscarriages)
SIGNS
Diabetes does not usually present with any typical signs.
INVESTIGATIONS
Newly diagnosed patient
• Blood glucose
• Urine ketones
• Urine protein
• Blood urea, electrolytes and creatinine
• Blood lipid profile (adults)
• ECG (adults)
Subsequent monitoring
• Blood glucose
• Glycated haemoglobin (HbA1c) - twice or thrice a year, if available
• Blood lipid tests - annually, but more frequently if levels abnormal
• Blood urea, electrolytes and creatinine - annually, but more frequently if levels abnormal
• Urine protein - annually
• Eye examination - annually, but more frequently if findings abnormal
• Other tests as clinically indicated
NOTE: Urine glucose should not be used for the diagnosis and management of diabetes. The correlation between urine tests and simultaneous blood glucose is poor. In occasional circumstances, it may be used to monitor patients with diabetic ketoacidosis when blood glucose testing is unavailable. In such a situation, a fresh urine sample, taken several minutes after complete emptying of the urinary bladder, or while a urethral catheter is in place, must be used whenever urine is used for glucose testing.
TREATMENT
Therapeutic objectives
The objectives of long-term diabetes treatment are to:
• Relieve symptoms and maintain fasting (4-6 mmol/L) and 2-hour post-meal (4-8 mmol/L) blood glucose levels within the normal limits.
• Prevent acute diabetes complications such as hypoglycaemia, ketoacidosis and the hyperosmolar state.
• Prevent the chronic complications of diabetes, namely; blindness, limb amputation, kidney disease, nerve damage, strokes, heart attacks and neonatal abnormalities.
These objectives can only be achieved by strict blood glucose control and regular screening for diabetes complications. Regular follow-up of all individuals with diabetes is therefore important to assess their metabolic control.
Non-Pharmacological Treatment
Diet
All patients with diabetes require diet therapy. All patients (and close relations who cook or control their meals) must be referred to a dietician or diet nurse for individualized meal plans. In general, patients must avoid ‘free’ or refined sugars, such as in soft drinks, or adding sugar to their beverages. ‘Diet’ soft drinks, which contain a sweetener and not glucose, may however be used. Complex carbohydrates are to be encouraged.
Most of a day’s diet must consist of carbohydrates (60%), protein (15%) and fat (25%) mostly of plant-origin and low in animal fat. The total caloric content (portions) of meals must be reduced and the amount of fibre in the meal increased in those who are also overweight or obese. Some healthcare professionals advice patients to eat only unripe plantain (‘apem’ in the Twi language). This practice is improper and must be discouraged.
Exercise
Regular, simple exercise (e.g. walking 1 hour daily) is helpful in ensuring good blood glucose control. All advice on exercise must give consideration to the patient’s age and the presence of complications and other medical conditions.
Pharmacological Treatment
(Evidence rating: A)
• In older patients, who usually have Type 2 diabetes, diet alone should be tried first.
• When diet fails to achieve satisfactory control, non-obese patients are usually treated with a sulphonylurea drug, and obese patients with a biguanide (metformin).
• Avoid metformin and long-acting oral anti-diabetic drugs, such as chlorpropamide and glibenclamide in the elderly and other individuals with poor kidney and liver function.
• Oral anti-diabetic drugs should be avoided in Type 1 patients and should not be used during pregnancy and breast-feeding.
• Insulin is always indicated in a patient who has been in ketoacidosis, and in most young patients who usually have Type 1 diabetes. Insulin is also indicated in older or Type 2 patients when oral anti-diabetic drugs cease to be effective and in all pregnant and breast-feeding women
• The starting dose of any long-term treatment for diabetes must initially be low, with increments in the dose over several days or weeks according to results of blood glucose testing
• Hypoglycaemia is a potential side-effect with all oral anti-diabetic drugs (except Metformin) and Insulin
Sulphonylureas
All sulphonylureas are of equal potency and efficacy. The recommended total daily doses for the commonly available ones are: -
• Tolbutamide, oral, 250 mg-1 g, 8-12 hourly
• Gliclazide, oral, 40-160 mg 12 hourly
• Glibenclamide, 2.5-10 mg as a single dose in the morning (if required, not more than 5 mg could additionally be given in the evening - maximum total dose 15 mg per day)
• Chlorpropamide, 100 - 500 mg as single dose daily
Sulphonylureas are best taken with meals. Tolbutamide and Gliclazide are short-acting and are preferred in the elderly and those with mild kidney disease. In general sulphonylureas should be avoided in all patients with liver disease and used with care in kidney disease.
Biguanides
The only biguanide available in Ghana is Metformin.
Dose: Metformin, oral, 500 mg-1 g 12 hourly
Metformin is best taken with, or soon after, meals.
Combined oral therapy
Type 2 individuals not responding to maximum tolerable doses of sulphonylureas or Metformin alone, could be given a combination of a Sulphonylurea and Metformin. Two different sulphonylureas should never be used together.
Insulin
• Insulin therapy should usually begin with teaching the patient the correct technique for subcutaneous injections, as self- injections are to be strongly encouraged.
• Patients should be made aware of the different appearance of different kinds of insulin (soluble/regular which is fast-acting = gin clear; NPH or Lente which are intermediate-acting = cloudy; pre-mixed insulin preparations containing both soluble and NPH insulin = cloudy)
• Cloudy Insulins (intermediate-acting or pre-mixed) can only be given subcutaneously and SHOULD NOT be injected IM or IV. Only soluble/regular insulin may be given by the IM or IV route during emergency treatment.
• Patients should be made aware of the strengths of insulin and the kind of syringes to be used. To avoid confusion, 100 U/ml insulin must be administered ONLY with 0.3 ml, 0.5 ml or 1 ml U-100 syringes calibrated for this strength of insulin.
• Insulins currently available in Ghana are preferably injected 15-30 minutes before a meal.
• Two injections daily (before breakfast and dinner) of an intermediate-acting or pre-mixed Insulin give better blood glucose control than once daily injections. Older patients and those with kidney disease may sometimes manage adequately on a single daily injection.
• Two-thirds of the total daily insulin requirement is given before breakfast, and the remainder before the evening meal.
• Insulin requirements vary from patient to patient irrespective of age and body weight.
REFER
Referral of individual patients to a dietician or diet nurse is highly recommended where the service is available. All pregnant women and children with diabetes as well as diabetes patients who have any of the following must be referred to a regional or teaching hospital for specialist care:
• Persistently poor blood glucose control
• Poor blood pressure control
• Frequent diabetes-related admissions
• Visual impairment
• Foot ulcers or gangrene
• Other chronic complications of diabetes
• Persistent proteinuria
