chapter 26 Diabetes
INTRODUCTION AND OVERVIEW
Diabetes mellitus is classified into several types:
Once a diagnosis of diabetes is established, management of diabetes is aimed at secondary prevention strategies through control of blood sugar levels, correction of micronutrient deficiencies and active risk factor management. The long-term effects of diabetes are largely due to its effect on blood vessels leading to both micro and macro vascular disease.
RISK FACTORS AND PRIMARY PREVENTION
In order to establish advice for patients on how to prevent or delay the onset of diabetes, it is important to:
AETIOLOGY
Type 1 diabetes
Type 1 diabetes constitutes around 5–10% of diabetes cases. Aetiological factors are the following:
Type 2 diabetes
Type 2 diabetes constitutes around 90–95% of cases of diabetes. Aetiological factors are the following:
Type 2 diabetes, being strongly related to lifestyle, is most common in affluent countries, where there is abundant food along with sedentary occupations and a significant uptake of labour-saving devices. Within those affluent countries, however, type 2 diabetes is more common among lower socioeconomic groups, where poor-quality food, social disadvantage and poorer education have their impact. In either case, the cause of the condition being largely lifestyle related also means that it is preventable and can be managed with appropriate and sustained lifestyle change. To illustrate how important simple lifestyle factors are in diabetes prevention, never smoking, having a BMI < 30, exercising moderately for 3.5 hours per week and following a few healthy dietary principles (high intake of fruit, vegetables and wholegrain bread, and low meat consumption) compared with not having any of those four factors was associated with a 93% reduced risk of developing type 2 diabetes over 8 years of follow-up.3
Gestational diabetes
The hormones responsible for promoting fetal growth and development increase markedly in the last 20 weeks of pregnancy. Human placental lactogen in particular has anti-insulin effects. Despite higher insulin levels in the last trimester, there is a reduction in peripheral insulin sensitivity and higher basal hepatic glucose output.
Prediabetes and metabolic syndrome
Prediabetes is a state in which the body does not respond properly to insulin, so blood glucose levels are higher than normal, but not in the range for a diagnosis of diabetes. It is generally asymptomatic. Progression to a diagnosis of diabetes is not inevitable.
Metabolic syndrome is a recognised precursor to the development of type 2 diabetes. A diagnosis of metabolic syndrome requires three of the risk factors listed in Box 26.1 to be present.4
Significance of metabolic syndrome
Metabolic syndrome is a cluster of risk factors that increase the risk of developing diabetes, heart disease and stroke. It is also known as syndrome X, dysmetabolic syndrome and insulin resistance syndrome. Incidence increases with age. It is thought to be the result of a combination of genetic predisposition and lifestyle factors, including dietary and exercise habits.
PRIMARY PREVENTION
Nutritional and environmental
Pre-conception counselling and pregnancy
Maternal malnutrition and overnutrition during pregnancy are associated with subsequent type 2 diabetes in the offspring.5 Primary prevention needs to start with pre-conception counselling of women planning pregnancy, with advice on exercise and nutrition to maintain optimal weight and nutritional status during the pregnancy.
Infant supplements
A systematic review of observational studies found that giving infants vitamin D supplements could protect them from type 1 diabetes.6 Infants given the supplement had an almost 30% reduced risk of diabetes compared with those who were not supplemented. This is particularly important in breastfed infants of vitamin-D-deficient mothers.
Weight management
Preventing or reversing metabolic syndrome involves weight loss and waist circumference reduction through diet and increased activity, and maintaining goal levels of blood pressure, lipids and lipoproteins and blood glucose. BMI per se is now seen as a less accurate marker of cardiovascular risk. It is not just the presence of excess weight but the pattern of weight distribution that is important. Abdominal or ‘apple’ obesity is the pattern associated with greater risk. The so-called ‘pear’ distribution of fat, mostly around the hips and legs, is less of a problem than the apple distribution. The measurement to determine which category a patient falls into is the waist–hip ratio. If this is above 1.0 for women or 0.9 for men, the person is said to have the apple distribution of fat; below these figures the person would be classified as having the pear distribution.
The mainstays of primary prevention of diabetes are:
Case detection
Proactive screening of asymptomatic patients
There is an asymptomatic phase of undetected diabetes mellitus that provides an opportunity for early detection, reducing the incidence of long-term complications. Microvascular complications such as retinopathy, neuropathy and renal disease are commonly already present at the time of diagnosis of type 2 diabetes.
The following groups of asymptomatic patients should be tested:7
Blood glucose level
The test of choice for diagnosis is fasting plasma glucose performed in an accredited laboratory. Random measures may be used.
Interpretation of blood glucose level (BGL) results:
Re-testing should be performed under the following circumstances:
People in high-risk groups with negative screening blood glucose tests are also at high risk for cardiovascular disease and should be encouraged to reduce their cardiovascular risk factors.
Glucose tolerance test
People found to have impaired glucose tolerance, where glucose levels are above normal but fall short of a diagnosis of diabetes, are at higher risk of later developing type 2 diabetes and also at higher risk of cardiovascular disease. Approximately one-third of people with impaired glucose tolerance will develop type 2 diabetes.
MANAGEMENT
INITIAL ASSESSMENT
History
Initial assessment of the patient with diabetes involves a comprehensive medical, social and lifestyle history:
Examination
Comprehensive physical examination, including:
Laboratory tests and further investigations:
INITIAL MANAGEMENT
The aim of initial management is to establish glycaemic control, normalise lipid and lipoprotein levels and motivate the patient to make significant and lasting changes to their lifestyle, including exercise and weight control.
A significant feature of the initial management phase includes patient education in self-monitoring, symptom awareness (including signs of hypoglycaemia), diet and exercise, and self-care.
A decision needs to be made about appropriate medication and supplements (see below).
Education
As is the case with the successful management of any chronic disease, the healthcare professional acts as informed advisor to the patient. It is the person living with diabetes who has to ‘walk the walk’, deciding on their level of compliance with recommended treatments. This involves ‘big picture’ decisions like starting oral hypoglycaemic agents or insulin treatment, or wholesale lifestyle adjustment, as much as the micromanagement of individual risk factors, such as choice of exercise program and the finer details of dietary components. For this reason, management plans must have mutually agreed, achievable goals.
The primary aim of treatment of diabetes is to optimise blood sugar control in order to increase longevity and quality of life, and to minimise complications of the disease. When devising a management plan, you will need to consider the patient’s level of education, cultural beliefs, preferences and financial resources. For example, although a personal trainer might be a desirable way to motivate a person to exercise regularly, this would not be affordable for many. A walking group might be an option.
Education also needs to include significant others in the patient’s life. Whoever has responsibility for food shopping and preparation in the household will need to be involved in education about dietary changes. Exercise programs will need to involve the encouragement of significant others, to aid compliance.
Home blood glucose monitoring is an essential part of the management of diabetes, initially under close supervision. In the early stages after diabetes is diagnosed, BGL readings three or four times a day are recommended. Once blood glucose levels stabilise, monitoring can be reduced to once or twice a day, one or two days a week.

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