La educación en valores en los procesos educativos actuales

The importance of strict glycaemic control has been alluded to earlier. Several methods are available to monitor glycaemic control namely: urine testing, fasting and/or postprandial blood glucose, regular self-monitoring of blood glucose and measurement of long-term glycaemic control.

1.5.1: Urine Glucose Measurement

Tests of urine glucose have been found to correlate poorly with plasma glucose values, ²⁶ as it depends on the renal threshold for glucose

excretion. This is influenced by such factors as old age and Pregnancy.

However, in resource poor rural settings, Urine glucose measurement may be the only available means of Glucose Measurement.

1.5.2: Plasma Glucose Measurement

The plasma glucose levels have the limitation of only reflecting the patients control at that particular moment, so that the results may not reflect a patient’s usual metabolic state. ²⁶

1.5.3: Self Monitoring of Blood Glucose (SMBG)

SMBG allows patients to evaluate their individual response to therapy and assess whether glycemic targets are being achieved. Results of SMBG can be useful in preventing hypoglycaemia and adjusting medications, MNT, and physical activity.The frequency and timing of SMBG should be dictated by the particular needs and goals of the patients. ³²

1.5.4: Glycated Haemoglobin Measurement

Glycated haemoglobin measurement is the most objective means of assessing the patient’s long-term glycaemic control. ³²

In normal adults, about 90% of total hemoglobin (Hb) consist of two alpha chains and two beta chains (2α, 2ß) so called Hb A; HbA2 (2, 2) make up 2% and HbF (2, 2) make up approximately 1% of total hemoglobins. The remaining 7% of hemoglobin also consists of two alpha and two beta chains, with either glucose or its derivative attached to

the beta chain. If glucose is attached, the resulting hemoglobin is called Hemoglobin A1c (HbA1c). ²⁶

HbA1 is an electrophoretically fast-moving hemoglobin component that is present in normal persons and increases in amount in the presence of hyperglycaemia. It is formed by the non-enzymatic glycation of the amino acids valine and lysine on the beta chain of hemoglobin A. HbA1c is the major component of these hemoglobins and constitutes approximately 5% of total hemoglobins in non-diabetic persons. The other haemoglobins are known as HbA1a and HbA1b and they make up approximately 1% each of total haemoglobins in non-diabetic individuals. Because all these haemoglobins contain glucose or one of its derivatives, they are known collectively as HbA1.

The reaction between glucose and the beta chain of the haemoglobin is (1) slow (2) mostly irreversible (3) not mediated by an enzyme (4) continuous over the life span of the red blood cell (RBC), and (5) proportional to the glucose concentration to which the RBC is exposed.

Thus, the amount of the HbA1 or its major component HbA1c is a time integrated measure of the prevailing glucose concentration to which the RBCs have been exposed. As such, measurement of glycated haemoglobin gives an objective assessment of metabolic control over the lifespan of RBC i.e. the preceding 2 - 3 month. Normal whole blood

glycated hemoglobin in the non-diabetic individual is 4 - 6% of the total haemoglobin. On average, HbA1c value of 5 - 7% would reflect good control, while levels >8% would reflect poorly controlled diabetes. ²⁶ There are no clinically significant effectsof age, sex, ethnicity, or season on HbA1c test results.However, several haemoglobinopathies and chemically modified derivatives of haemoglobin interfere with some assay methods, independent of any effects attributable to shortened erythrocyte survival. HbA1c is falsely elevated when chromatographic methods measure an acutely generated intermediary aldimine in blood (prehaemoglobin A1c) e.g., in alcoholism as well as in the presence of uraemia or HbF; it is falsely lowered in conditions of shortened red blood cell lifespan (e.g., in anaemia and acute or chronic blood loss) or in patients with haemoglobinopathies (haemoglobins C, D, & S). ²⁶ Boronate affinity chromatographic assay methods are generally considered to be less affected by haemoglobinopathiesthan methods that separate glycated and non-glycated components based on charge differences. ³³ In addition, because different HbA1c assay methods can give different HbA1c values, the ADA recommends that laboratoriesuse only methods that are certified as traceable to the DCCT HbA1c reference. ³⁴

Hemoglobin A1c has become the pre-eminent factor for quantifying the risk of complications in patients with diabetes and for

monitoring glycaemia. ³² It is pertinent therefore, to routinely measure HbA1c in patients with DM with a view to keep it in the normal range and thus prevent or delay the onset of microvascular complications.

In this regard, it is recommended that glycated hemoglobin be measured at least 4 times a year for adequate assessment of metabolic control.

This measure has however, not been shown to affect the health of diabetic patients because glycated hemoglobin values remain fairly constant in an individual patient over many years. ³⁴ This, coupled with the clinical recommendation guidelines of the American Diabetes Association (ADA) to perform the HbA1ctest two times a year in patients who are meeting treatment goals may suggest less frequent tests in this part of the world where the facilities are not readily available and cost may be a limiting factor. ³²

Concentrations of other blood-based glycated proteins e.g., glycated serum/plasma proteins, fructosamine also reflect mean glycemia, but over a much shorter time thanHbA1c (15–30 days and 60–120 days respectively). However, the clinical utility of glycated proteins other than haemoglobin has not been clearly established, and there is noconvincing evidence that relates their concentration to the chronic complications of diabetes. ³⁵

1.6: Statement of the problem

Diabetic Foot Disease is one of the major long term complications of

Diabetes Mellitus (DM). Although many serious complications, such as kidney failure or blindness, can affect persons with diabetes, it is the complications of the foot that take the greatest toll. ³⁶ Foot problems account for more hospital admissions amongst patients with diabetes, than any of the other long-term complications. ³⁷

It is estimated that foot ulcers occur in approximately 15% of patients with DM and that 85% of Lower Extremity Amputation (LEA) in patients with DM are preceded by foot ulcers. ³⁶ LEA is a devastating event for individuals and their families with important economic consequences for them and the society. Expectedly, LEA was chosen by the WHO/IDF St Vincent Task Force as a major endpoint of diabetic foot disorders, and a 50% reduction was the target set to be achieved within a 5-year period;

however, published data on trends in amputation rates are not encouraging. ³⁸

The spectrum of foot lesions varies in different regions of the world due to differences in socio-economic conditions, standards of foot care and quality of available footwear. ¹³ Prevalence rates of Diabetic Foot Ulceration (DFU) range from 5.3% in the United Kingdom (UK) to 11.9% in Algeria. ³⁹ In Nigeria, reported prevalence rate varies from 0.97% to 19.3% making diabetic foot ulceration the leading indication for non-traumatic lower extremity amputation (LEA) in recent times. ⁴⁰ This compares with data from Western countries where diabetes remain

the commonest cause of non-traumatic amputation in adults. ⁴¹

In the UK, a report from a health care district showed a 50% increase in amputation between 1990 and 1994, while recent data from the US showed that in the diabetic population, rate of amputations per year over a 10-year period (1989 – 1998) remained the same. ⁴² The consequences of the high prevalence of foot lesions in persons with diabetes are prolonged hospital stay, reduced quality of life (not only of affected individuals but also of family members and other carers), and even death.^. In addition, facilities for post amputation rehabilitation are often unavailable or unaffordable in many developing countries. ³⁰

All of these are important contributors to the overall economic burden of the diabetic foot disorders. This burden include both direct health care costs, the cost of services that are involved in the identification, treatment and care of patients as well as indirect costs (those of loss of life or function and the benefits to society which must be forgone as a result of its members ceasing to contribute their skills).

For example, the average cost for primary healing in the USA has been estimated to be between US$ 7 000 - 10 000 while the direct cost of an amputation associated with the diabetic foot is estimated to be between US$ 30,000 - 60 000, depending upon the level of amputation. ²⁹ Similarly, report from a Nigerian study estimated the mean costs for successfully treating a patient with DMFS to be Nigerian Naira (NGN)

180 581.60 while the total costs of care incurred (bed fees, medications, etc.) ranged from NGN 20400.00 to NGN 278 029.00. ³¹

In addition, disturbingly high mortality rate associated with DFU has been reported in Nigeria. ⁴³

It is therefore cost effective to prevent development of foot lesions by early identification of risk factors and optimal prevention according to international consensus recommendations (patient education, foot care and appropriate footwear). ⁴⁴

1.7: Research Question

To determine if there is a difference in the prevalence of known risk factors for diabetic foot ulceration between Type 2 DM patients with diabetic foot disease and those without foot disease.

1.8: Justification of study

Relevance of the project to the individual derives from its ability to raise awareness on identification of risk factors for diabetic foot disease and thus put in place strategies to prevent morbidity and mortality associated with this scourge. This will impact favorably on the socioeconomic life of the individual in particular and the society at large, in terms of reduction of absence from work, cost of management and loss of limb or life.

The relevance of the project to the practice of the discipline lies in the ability to complement efforts into studies of the diabetic foot which

has been described ‘as the single greatest growth area in diabetes work, (both research and clinically related). ³⁶ Unfortunately, much of the work has been done in Western and relatively affluent countries while the third world countries continue to grapple with increasing burden of diabetes mellitus and diabetes related complications, in addition to widespread communicable diseases and other daunting health–related problems.

There is also a relative paucity of data on the subject amongst Nigerians.

In view of the expected increase in the burden of diabetes worldwide, the burden of diabetic foot disease and its sequelae are expected to increase even further. There is thus a pressing need for studies on the burden and risk factors for diabetic foot ulceration amongst Nigerians. The insight provided will greatly assist in the development and evaluation of clinical diagnostic as well as preventive strategies and public health practices. This is of great importance as intensive preventive strategies, education of the patient, carers and health professionals on foot care and the use of appropriate footwear is cost effective or even cost saving if applied to patients with risk factors for foot ulceration. In this regard, it is hoped that simple efforts of early identification of patients at risk, care and education will be cost saving in Nigerians with type 2 DM as has occurred in the more developed countries. ³⁶

Finally, it is hoped that studies like this will help to generate awareness

amongst healthcare decision makers so they can understand the devastation caused by diabetic foot disease and assign adequate resources.

1.9: Aims and Objectives 1.9.1: General objective

To determine risk factors for foot ulceration amongst Nigerian patients with Type 2 diabetes mellitus attending the University College Hospital, Ibadan, South Western Nigeria.

1.9.2: Specific objectives

1. To determine the prevalence of Peripheral neuropathy, Peripheral vascular disease, use of ill-fitting footwear, as well as current or previous ulceration and/or amputation among patients with type 2 DM;

2. To compare the prevalence of risk factors of DFU between the patients with foot ulcers (cases) and those without (control subjects);

3. To determine the relationship between the prevalence of these risk factors and some clinical variables. The variables of interest are socio-demographic characteristics (including age and sex of patient, level of education, footwear habit, as well as alcohol use and smoking habits); duration of diabetes and degree of glycaemic control, as well as presence of extrapedal

complications of diabetes mellitus (retinopathy, nephropathy, cerebrovascular disease).

CHAPTER TWO: LITERATURE REVIEW 2.1. Diabetic Foot Disease

2.1.1: Introduction

Diabetic foot disease is defined as infection, ulceration and/or destruction of deep tissues of the foot associated with neuropathy and/or peripheral arterial disease in the lower extremity of people with diabetes.⁴⁵ Globally, diabetic foot disease is a major medical, social and economic problem that is seen in every continent and constitutes a major burden to the patient and the health care system. ⁴⁶ Despite the increase in diabetic foot related research activity, foot ulcerations remain common in both main types of diabetes, although the majority of cases occur in people with T2DM. ⁴⁴ Given the multi factorial origin of diabetic foot ulcers, a systematic approach to management is essential.

2.1.2: Anatomy of the Foot

The human foot combines mechanical complexity, structural strength and provides flexibility and resiliency. The foot serves to support the body weight and to propel the body forward in walking and running.⁴⁷ Structurally, the foot has three main parts: the forefoot, the mid foot, and the hind foot. The forefoot is composed of the five toes (or phalanges)

and their connecting long bones (metatarsals). The mid foot has five irregularly shaped tarsal bones, forms the foot's arch, and serves as a shock absorber. The bones of the mid foot are connected to the forefoot and the hind foot by muscles and the plantar fascia. The hind foot links the mid foot to the ankle (talus).

The skin of the dorsum of the foot is about 2mm thick and contains hair follicles, sweat glands and scanty sebaceous glands. The plantar skin is 4 - 5mm thick with the thickest areas covering the heels and the distal metatarsals: it is richly innervated and has numerous sweat glands. The foot has three arches that serve to hold up weight; these are the transverse arch, the medial and the lateral longitudinal arches. Most of the muscles of the foot are arranged in layers on the plantar surface of the foot. There they connect to and move the toes as well as provide padding underneath the sole of the foot. There are five muscle groups namely; the anterior tibial, posterior tibial, peroneal tibial, and the extensors and flexors; the interosseous muscles serve to maintain balance between the flexor and extensor groups. The largest and strongest tendon in the foot is the Achilles tendon, which extends from the calf muscle to the heel.

Ligaments hold the tendons in place and stabilize the joints. The longest of these, the plantar fascia, forms the arch on the sole of the foot from the heel to the toes.

The foot derives its arterial supply from the popliteal artery, which divides into anterior and posterior tibial arteries; the anterior tibia becomes the dorsalis pedis in the foot.

Venous drainage is via venous plexuses that drain into the long and short saphenous veins and then to the popliteal veins. The main nerve to the foot, the tibial nerve, enters the sole of the foot by running behind the medial malleolus. Several other nerves run into the foot on the outside of the foot and down. ⁴⁸

2.1.3: Burden of Diabetic Foot Disease

Foot problems are common and life-threatening, and they place an enormous financial burden on people with diabetes and their families, the healthcare sector, and society as a whole. Throughout the world, up to 70% of all leg amputations are done in people with diabetes. It has been noted that people with diabetes are 25 times more likely to have lower limb amputation than the general population. ¹³

In most countries, a continuous registration system is not in place, hence amputations are widely underestimated, but worldwide the prevalence of lower-extremity amputations (LEA) ranges from 0.2 - 4.8%; the annual incidence ranges from 46.1- 936 per 100,000 people with diabetes. The rate of LEA is reported to be 2.6 times higher in men than women, adjusted for age and duration of diabetes. It is also estimated that foot ulcers occur in approximately 15% of patients with diabetes and that 85%

of lower limb amputations in patients with diabetes are preceded by foot ulceration. ⁴⁶ The reported frequencies of ulceration and amputation among diabetic populations vary considerably both on a national and international level. These variations can be attributed to differences in ethnicity, local medical and/or surgical practices/provision/accessibility, diagnostic criteria used, and methods of data collection. ⁴⁹ Diabetic foot ulcers are reported to be much more common in patients with neuropathy - the annual incidence rises from less than 1% in those without neuropathy to greater than 7% in those with established neuropathy. ⁵⁰ Prevalence of foot ulceration and its attendant risk factors range from 5.3% and 41.6% respectively in UK, to 11.9% and 58.4% respectively in Algeria. However, it should be noted that while the former was a population-based study involving only persons with T2DM, the latter was clinic-based. ³⁹ In Canada, it is estimated that 4 - 10% of people with diabetes will develop a foot ulcer in their lifetime, and 14 - 24% of these people will require an amputation. ⁵¹

Foot ulcerations are a leading cause of hospitalization amongst patients with diabetes in many developing countries worldwide, resulting in prolonged hospital stays and increased morbidity and mortality. ³⁰ Prevalence rates of LEA in hospital-based studies conducted in some African countries ranges from 33% in Tanzania, to 38% in Burkina Faso, 53% in Ethiopia, and 55% in Kenya. ⁵¹ Prevalence rates of diabetic foot

ulcer in Nigeria, range from 0.97% in the early 1960’s, to 19.3% in 1996;⁴⁰ Osuntokun et al in 1971 reported a prevalence of 3%, ¹⁷ Adetuyibi in 1976 reported 3.8%, ⁵² while a more recent study by Ndububa reported a prevalence of 19.3%.⁵³

Currently, it is of note that, diabetic foot ulceration is reported to be the leading indication for non-traumatic lower limb amputation in Nigeria, ⁵⁴ as shown by a review of non-traumatic amputations performed in four tertiary hospitals in Nigeria. ^{54 - 57} In fact, the rising lower limb amputation rate from diabetic foot disease has changed the old trend of indications for amputation to what had obtained in the developed countries. Indeed, diabetic foot ulceration in the last 40 years in Nigeria has moved from being “rare” to being “common” in our practice setting. ⁵⁴

2.2: Risk Factors of Diabetic Foot Ulcers

Ulcerations do not occur spontaneously –there are many warning signs or shadows. Often it is an interaction between environmental hazards and various risk factors in the lower limb. ⁵⁸

Usually several mechanisms are involved simultaneously. Table 2 shows the major risk factors associated with diabetic foot ulceration.

Table 2: Risk factors of Diabetic Foot Ucers

Previous ulcer/amputation Neuropathy Sensorimotor Trauma

Poor footwear Walking barefoot Falls/accident

Objects inside shoes Biomechanics

Limited joint mobility Bony prominences

Foot deformities/osteoarthropathy Callus

Peripheral Vascular Disease Socioeconomic Status

Low social position Poor access to healthcare Non compliance/neglect Poor education

Source: Consensus document of the International Working Group on the Diabetic Foot, 2007.

2.2.1: Diabetic Neuropathy

Diabetic neuropathy is defined as ‘the presence of symptoms and/or signs of peripheral nerve dysfunction in people with diabetes after exclusion of other causes.’ ⁵⁹ Its prevalence increases with age and duration of diabetes and it may be the presenting feature of T2DM as demonstrated in the UKPDS study where >11% of patients had neuropathy at diagnosis. ⁶⁰

It is estimated that the prevalence of diabetic neuropathy in patients with T2DM is 32% overall and more than 50% in patients over 60 years of age. ⁶¹ In Africa, various studies have reported that foot complications are mostly caused by infection and/or peripheral neuropathy. ¹³ In this regard, reported incidence of peripheral neuropathy in some African countries range from 4% in Zimbabwe, to 46.4% in Uganda, 59% in Malawi, and 68% in Nigeria. ¹³

Neuropathy promotes ulcer formation by decreasing pain sensation and perception of pressure, by causing muscle imbalance that can lead to anatomic deformities, and by impairing the microcirculation and the integrity of the skin. Autonomic neuropathy produces chronic venous swelling due to loss of normal vascular tone and thermal regulation while motor peripheral neuropathy leads to muscle weakness and intrinsic

muscle atrophy in the hands and feet. These patients can develop bunion, claw toe, and hammertoe deformities due to muscle imbalance. ⁶²

In addition, they develop dry cracked skin (due to autonomic dysfunction), allowing the entry of bacteria. Nail deformity or pathologic proliferation may make the areas adjacent to the nails foci for skin breaks and/or infections. ⁶² Development and progression of neuropathy are associated with such clinical variables as increasing age and duration of DM. ⁶³

The neuropathies of diabetes comprise a number of distinct subtypes that affect the somatic and/or autonomic divisions of the nervous system, of which the chronic distal symmetric sensorimotor polyneuropathy (DPN) is generally accepted to be the commonest variety. ⁶⁴ Although, DPN is a diagnosis of exclusion, complex investigations to exclude other conditions are rarely needed.

The need to identify simplified criteria has resulted in the development of at least two simple screening tests: the United Kingdom Neuropathy Screening Test and the Michigan Neuropathy Screening Score. ⁶⁴

Table 3 below shows the classification and staging of diabetic neuropathy adapted from Consensus Panel, Report and Recommendations of the San Antonio Conference on Diabetic Neuropathy (1988). ⁶⁴