DIABETES MELLITUS

Metabolic disease resulting from insulin insufficiency or ineffectiveness, due to decreased insulin secretion,
or peripheral resistance to the action of insulin, or a combination of the two.

Causes

  • Type 1: decreased insulin production due to autoimmune destruction of the pancreas. Usually starts at a young age
  • Type 2: insulin resistance, usually combined with insufficient production of insulin as the disease progresses.
    Usually starts in adulthood
  • Secondary diabetes: due to other identifiable causes, e.g., Cushing’s syndrome, chronic pancreatitis, etc.

Risk factors

  • Type 1: genetic factors, environmental factors (e.g., some viral infections)
  • Type 2: family history, unhealthy diet, obesity, lack of exercise, smoking

Clinical features

  • Excessive thirst, excessive fluid intake (polydipsia)
  • Excessive urine production (polyuria)
  • Tiredness
  • Loss of weight (especially type 1)
  • Increased appetite (polyphagia)
  • Generalized itching
  • Blurred vision
  • Type 2 diabetes often only presents with minor aspecific  symptoms, and it is diagnosed either by screening or when the patient presents with complications

Complications

  • Acute coma due to diabetic ketoacidosis, or hyperosmolar hyperglycaemia (see next section), or hypoglycaemia
  • Stroke, ischaemic heart disease, kidney failure
  • Blindness, impotence, peripheral neuropathy
  • Diabetic foot which may lead to amputations

Differential diagnosis

  • Diabetes insipidus, HIV/AIDS, TB

Investigations

  • Blood glucose (fasting, random, and/or 2 hours after 75 mg of glucose)
  • Urine: for glucose, and ketones (in type 1)
  • HbA1c – Glycated haemoglobin 1c

Diagnostic criteria

1 Fasting blood sugar >7.0 mmol/L (126 mg/dl)
2 Two-hour blood sugar after 75 mg of glucose >11.1
mmol/L (200 mg/dl)
3 HbA1c >6.5%
4 In a patient with classical symptoms of
hyperglycaemia: Random Blood Sugar >11.1 mmol/L
(200 mg/dl)
Caution
  • In the absence of unequivocal hyperglycaemia (very high levels of blood sugar), criteria 1-3 should be
    confirmed by repeated testing. One single slightly elevated blood sugar in the absence of symptoms IS
    NOT DIAGNOSTIC for diabetes

General Management

Goals of treatment

  • Treatment of hyperglycaemia
  • Treatment of associated risk factors
  • Prevention and treatment of acute and chronic  complications

Life style modifications

  • Diabetic diet
  • Weight loss if overweight
  • Regular physical exercise
  • Moderate, or no alcohol intake
  • Smoking cessation

Management of risk factors

  • Assess for other risk factors (hypertension, obesity, smoking, etc.), and manage accordingly
  • Hypertension: target BP 120/80, first line medication are ACE inhibitors (renal protection
    effect), e.g., enalapril (see section 4.1.6)
  • Dyslipidaemia: consider statin treatment, e.g. atorvastatin 20-40 mg once daily or simvastatin
    20-40 mg once daily in the evening, especially if:

    • Ischaemic heart disease or cerebrovascular disease already present
    • Age >40 years
Caution
  • Do not use beta blockers, e.g., atenolol in diabetes

Management of complications

  • Assess for complications (renal disease, eye problems, diabetic foot, peripheral neuropathy,
    heart problem, stroke), and refer/ treat accordingly
  • Aspirin 75-100 mg/daily in ischaemic heart disease, or stroke
  • Amitriptyline 10-25 mg at night (max 100 mg in divided doses) for peripheral neuropathy
  • Atorvastatin 20-40 mg once a day in ischaemic heart disease, or stroke

Treatment targets

  • Fasting blood sugar <7 mmol/l
  • Postprandial sugar <10 mmol/l
  • HbA1c <7% (7.5 % for elderly)

Elderly people are at higher risk of hypoglycaemia. Monitor carefully, and do not aim at very strict control of blood sugar.

Management of Type 1 Diabetes

Insulin SC: 0.6 -1.5 IU/kg/day
Children <5 years: start with 0.5 IU/Kg/day, and refer to a
paediatrician
TYPE OF
INSULIN
USUAL
PROTOCOL
ACTION
ONSET PEAK DURATION
Insulin
short acting,
regular
soluble (e.g.
Actrapid)
3 times
daily, 30
minutes
before
meals
30
minutes
2–5
hours
5–8
hours
Insulin
intermediate
acting,
NPH, (e.g.
Insulatard)
Once or
twice daily
(evening ±
morning)
1–3
hours
6–12
hours
16–24
hours
Insulin
biphasic,
mixture of
regular and
NPH (e.g.
Mixtard
30/70)
Once or
twice daily
30
minutes
2–12
hours
16–24
hours

Preferably, a combination of intermediate and short acting insulin should be used, in the following regimens e.g.,

  • Pre-meals short acting insulin (e.g. actrapid), and evening intermediate acting insulin (e.g. Insulatard).
    The evening dose should be 40-50% of the daily dose (basal-bolus therapy)
    OR
  • Twice daily premixed insulin Mixtard: usually 2/3 of total dose in the morning and 1/3 in the evening, 30
    minutes before meals
Note
  • Patients on insulin should measure their blood glucose level at least twice daily (before breakfast, and before
    dinner), and insulin doses adjusted accordingly
  • More frequent pre- and post-meals measurements are required to adjust the doses especially with a basal-bolus therapy.
Caution
  • Oral antidiabetic medicines are NOT used in type 1. Metformin can be used but only under specialist advice

Management of Type 2 Diabetes

First line

  • Life style modifications
    • If sugar levels not very high, and patient is willing, try lifestyle modifications for 3 months, and
      reassess


If lifestyle modifications not enough, and/or sugar level initially very high, start on:

  • Metformin 1.5-2 g daily in divided doses at meals (start with 500 mg once a day for one week,then
    increase by 500 mg every week until target control is achieved)

If treatment targets not achieved with lifestyle modifications and metformin, add a second line
drug.


If intolerance or contraindication to metformin, start directly with second line

Second line

  • Glibenclamide 5 mg once daily with meals, initially
    Elderly: 2.5 mg daily (but see caution below) adjusted according to response up to a maximum
    of 10 mg in divided doses
  • 0r Glimepiride 1-4 mg once daily before or with the first meal of the day
    • Start with lowest dose, and increase every 1-2 weeks according to response

If control not achieved, add basal insulin (third line)
Third line

  • Insulin SC NPH (Insulatard) 8 IU (or 0.3 IU/Kg) in the evening, increase by 2-4 IU every 3-7 days until fasting blood glucose is in range

If control still not achieved, consider a full insulin regimen. Stop glibenclamide/glimepiride, but
maintain metformin if possible

  • Biphasic insulin (e.g. Mixtard 30/70) twice a day, 2/3 total dose in the morning before breakfast, and 1/3 in the evening before supper
    • E.g., Starting dose: 10 IU SC morning, 5 IU SC evening, increase by 4-5 IU/weekly. Adjust
      morning dose as per pre-supper blood glucose, and evening dose as per pre-breakfast blood glucose

    OR

  • Basal-bolus regimen: 0.4-0.6 IU/kg/day, half is given as basal insulin (e.g. Insulatard) in the evening, and half given as rapid insulin 30 minutes before meals
    • Adjust basal dose according to fasting blood sugar, and pre-meals insulin according to pre- and postmeals blood sugar levels
Caution
  • Glibenclamide: Use with caution/lower doses in elderly patients because of risk of prolonged hypoglycaemia.
    Preferably use glimepiride if available.
  • Metformin is contraindicated in advanced kidney disease
  • Do not use oral anti-diabetics in acute complications, and in acutely sick patients: use insulin for initial
    management

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