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VOLUME 15 NUMBER 1 • JULY 2018
DIABETES GUIDELINES
SA JOURNAL OF DIABETES & VASCULAR DISEASE
Type 2diabetes is associatedwith specific long-termadverse health
consequences, including retinopathy, nephropathy, neuropathy and
cardio-, cerebro- and peripheral vascular diseases.
The clinical stages of hyperglycaemia include intermediate
hyperglycaemia (impaired fasting glucose and impaired glucose
tolerance), which represents a high-risk state for development of
future diabetes and cardiovascular disease.
When assessing a patient with diabetes, a wide array of potential
aetiologies needs to be considered. Type 2 diabetes is a diagnosis of
exclusion after careful investigation for and exclusion of other
causes (Table 1).
Screening and diagnosis
In patients with symptoms of type 2 diabetes (polyuria, polydipsia,
blurred vision, weight loss) or metabolic decompensation (diabetic
keto-acidosis or hyperosmolar non-ketotic state), the diagnosis is
confirmed if one or more of the following are present:
• Random plasma glucose ≥ 11 mmol/l or fasting plasma glucose
(FPG) ≥ 7 mmol/l
• HbA
1c
≥ 6.5%
Type 2 diabetes is diagnosed in asymptomatic patients by any one
of the following tests, which must be confirmed on separate days
within a two-week period:
• FPG ≥ 7 mmol/l
• Two-hour post-load plasma glucose [oral glucose tolerance test
(OGTT)] ≥ 11 mmol/l
• HbA
1c
≥ 6.5%
Bedside or point-of-care devices (HbA
1c
or glucose) should not be
used to make the diagnosis.
Impaired fasting glucose and impaired glucose tolerance
(prediabetes) are present when two consecutive tests on different
days confirm FPG 6.1–6.9 mmol/l or two-hour post-load plasma
glucose 7.8–11.0 mmol/l, respectively.
Asymptomatic individuals at high risk for diabetes should be
screened using FPG, OGTT (preferred) or HbA
1c
at least every three
years, or more frequently if initial screening results are abnormal,
or if they are at very high risk. This includes all adults who are
overweight (BMI > 25 kg/m
2
or > 23 kg/m
2
in Asians), and have
one or more of the following risk factors: physical inactivity,
hypertension, a first-degree relative with diabetes, dyslipidaemia,
polycystic ovarian syndrome, high-risk race/ethnicity, history of
cardiovascular disease, gestational diabetes or baby > 4 kg, previous
impaired FPG or OGTT, or other conditions associated with insulin
resistance (severe obesity, acanthosis nigricans).
Management
Diabetes self-management education and support (DSME)
All people with diabetes and their families should be provided with
the education and support for self-management so that they can
effectively manage the disease at home themselves. DSME has been
shown to be associated with better glycaemic control and is one of
the strongest predictors of disease progression and development of
diabetes complications.
Lifestyle change and medical nutrition therapy (MNT)
Behaviour change, physical activity (aerobic and resistance exercise)
and healthy nutritional choices can achieve modest weight loss and
improve outcomes in overweight and obese individuals with type 2
diabetes and prediabetes, and are the essential foundation of every
patient’s management programme. MNT can reduce HbA
1c
by up
to 2%. Nutritional recommendations should be individualised,
aiming at a high-quality diet consistent with metabolic goals and
sensitive to ethnic, cultural and socio-economic needs, so that it is
sustainable. There is no one recommended diet that is considered
superior, or ideal in respect of which percentage of calories
should come from carbohydrates, fat or protein. Macronutrient
distribution should be individualised to suit the patient. Refined
carbohydrates high in sugar, fats and sodium should be replaced
with whole grains, legumes, milk, vegetables and fruit. Mono-
unsaturated fats are preferred to saturated fats and foods rich in
long-chain omega-3 fatty acids, such as fatty fish, nuts and seeds,
are recommended for cardiovascular risk prevention. Processed
and fatty red meats should be limited. The long-term health risks
associated with high-fat, low-carbohydrate and very-low-calorie
diets are uncertain and these diets are not recommended. Whole
foods are the best source of micronutrients and unless there are
specific clinical indications, vitamins and supplements are not
recommended.
Glycaemic targets
In most patients, management should aim to achieve and maintain
HbA
1c
≤ 7% (self-monitored plasma glucose (SMPG) fasting or
preprandial 4–7 mmol/l and postprandial 5–10 mmol/l). In newly
diagnosed patients who are in good health, as long as it can be
achieved safely, target HbA
1c
≤ 6.5%can prevent further retinopathy
and nephropathy. In elderly patients and those with limited life
expectancy, multiple co-morbidities, severe vascular disease,
advanced chronic kidney disease, recurrent severe hypoglycaemia
or hypoglycaemia unawareness, HbA
1c
7.1–8.5% is acceptable.
Pharmacotherapy for type 2 diabetes
When added to metformin, most drug options for type 2 diabetes
are equally efficacious at lowering blood glucose with reductions
in HbA
1c
of approximately 0.8–1.2%. However, in clinical practice
the response to individual drugs varies widely between patients,
with some responding well and others not at all. Implementation
and intensification of lifestyle modifications also affect drug
efficacy. Therefore, drug selection should be individualised, based
not only on glycaemic targets, but also taking into consideration
hypoglycaemia risk, risk of treatment-associated weight gain and
other side effects, individual patient characteristics, treatment
complexity and cost. Maximum glucose lowering is usually evident
by six months.
Guidelines for step-wise pharmacotherapy for stable patients
with type 2 diabetes with suboptimal glycaemic control, who
are being managed at primary care facilities, are shown in Table
2. Intensification (step-up) of treatment may be considered if the
HbA
1c
target is not achieved after three months or if HbA
1c
rises after
initiating new therapy. Patients with metabolic decompensation
who have severe symptomatic hyperglycaemia and those with
severe micro- or macrovascular complications should be managed
under specialist supervision.
Unless it is contra-indicated, metformin is the drug of first choice
and, as long as it is tolerated, should be continued indefinitely.
Most patients will require titration to 1 000–2 550 mg in two or
three divided doses and the optimal dose for cardiovascular benefit
in obese patients is 2 550 mg/day (850 mg TDS). If tolerability is
poor, consideration should be given to switching to the extended-
release (XR) formulation.