Diabetes is a chronic metabolic disease with metabolic abnormalitis and elevated levels of blood glucose, which causes complications in the heart, blood vessels, kidneys, nerves and eyes in a long term. The most common type of diabetes is type 2 diabetes, accounting for 90-95% of all people with diabetes (American diabetes association 2019). In type 2 diabetes, the body develops insulinresistance or the pancreas does not produce insulin enough. In type 1 diabetes the pancreas does not produce insulin at all or produces it little (World Health Organization 2016). Diabetes type 1 and 2 are extreme types, and between them, there are patients who have characteristics of both main groups. Both type 1 and type 2 diabetes occur in adults and children. Despite the different types of diabetes and
its progression if hyperglycemia occurs, patients are at risk of having the same complications. Therefore, more important than classification is preventing complications (Skyler et al. 2017).
1.2.1 Pathophysiology and classification of diabetes
The details of pathophysiology are better known in type 1 than in type 2 diabetes.
Based on previous studies, a combination of having first-degree relatives with type 1 diabetes and at least two autoantibodies is a strong predictor of diabetes (Insel et al. 2015). In type 2 diabetes, the demise of β-cells and dysfunction of the pancreas are undefined. Both deficient β-cell insulin secretion and insulin resistance often arise together in type 2 diabetes. In a recent review, genetic studies in general suggest that genes affect the dysfunction of insulin secretion more than insulin sentitivity (Laakso 2019). It is also associated with inflammation and metabolic stress, lifestyle and genetic factors (Insel et al. 2015, Skyler et al.
2017). Furthermore, a BMI ≥25 kg/m2 is regarded as a risk factor for diabetes (American Diabetes Association 2019).
Table 1 shows the classification of diabetes According to The American Diabetes Association (ADA 2019). The Finnish Diabetes Current Care Guidelines uses the same classification.
Table 1. Classification of diabetes (ADA 2019)
Type 1 diabetes
due to autoimmune β-cell destruction, usually leading to absolute insulin deficiency
Type 2 diabetes
due to a progressive loss of β-cell insulin secretion frequently in the background of insulin resistance
Gestational diabetes mellitus (GDM) (diabetes diagnosed in the second or third trimester of pregnancy and was not clearly overt diabetes prior to gestation
Specific types of diabetes due to other causes,
1. monogenic diabetes syndromes such as neonatal diabetes and maturity-onset diabetes of the young [MODY]
2. diseases of the exocrine pancreas such as cystic fibrosis and pancreatitis
3. drug- or chemical-induced diabetes such as with glucocorticoid use, in the treatment of HIV/AIDS, or after organ transplantation
In a new classification of diabetes type 2 there are five different subgroups (Ahlqvist et al 2018). In severe autoimmune diabetes (SAID) there are glutamate decarboxylase antibodies (GADA), insulin deficiency and poor metabolic control. In severe insulin-deficient diabetes (SIDD) there are deficiency of insulin and poor metabolic control but no GADA. Severe insulin-resistant diabetes (SIRD)is characterized by insulin resistance and obesity. In mild obesity-related diabetes (MOD), in spite of a high BMI there is no insulin resistance. Mild age-related diabetes (MARD) occurs in older people and has only plain metabolic derangements.
1.2.2 Diagnosis of diabetes
A diagnosis of diabetes is based on either the fasting plasma glucose (FPG) value or the 2-h plasma glucose (2-h PG) value during a 75 g oral glucose tolerance test (OGTT), or A1C criteria (International Expert Committee 2009, American Diabetes Association 2019). These tests may be used to both diagnose diabetes and to screen for prediabetes (American Diabetes Association 2019).
Normal fasting plasma glucose is ≤ 5.5 mmol/l (American Diabetes Association 2019) or ≤6,0 (World Health Organization 2016). In impaired glucose tolerance, values are 5.6-6.9mmol/l (American Diabetes Association 2019) and 6.1-6.9mmol/l (World Health Organization 2016). Diabetes can be diagnosed if fasting plasma glucose is ≥ 7.0mmol/l. 2-hour values less than 7.8mmol/l are normal in the oral glucose tolerance test and values of 7.8-11.0mmol/l means impaired glucose tolerance. Diabetes is diagnosed when 2-hour plasma glucose is over 11.0mmol/l.
Normal Hba1C is ≤ 42.0 mmol/mol and a Hba1C of ≥ 48.0 mmol/mol or ≥ 6.5%
means diabetes (American Diabetes Association 2019, World Health Organization 2016).
Finland uses the same criteria as WHO. Impaired glucose tolerance (IGT) and fasting glucose (IFG) are considered prediabetes. Abnormal glucose value should be checked and measured in different days if the patient does not have symptoms (thirst, polyuria, weight loss). In the event the patient has symptoms, a diabetes diagnosis can be based on one fasting glucose value, provided that it is ˃11.0 mmol/l (Diabetes: Finnish Current Care Guidelines 2020).
1.2.3 Prevalence of diabetes
The prevalence of diabetes worldwide has increased evently for the past three decades, doubling since 1980 to 422 million adults (8.5% of the adults aged 18 or
older) in 2014 (NCD Risk factor collaboration 2016). The causes are complex. The increasing prevalence of diabetes is related to increased numbers of people with excess weight and obesity, and decreasing physical activity.
In Finland, the prevalence of diabetes is assessed to be 11%, consisting mostly (89%) of type 2 diabetes (Laakso et al. 2016). The number of people with diabetes receiving reimbursement for the cost of diabetes medication increased 20%
between the years 2011-2016 and at the end of 2018 the number of people receiving reimbursement was 346,929 (Kela 2018).
1.2.4 Management of diabetes
The target for most adults with type 2 diabetes treated with oral diabetes medication alone is <7% (Hba1C 53 mmol/mol)( American Diabetes Association 2019). Tighter Hba1C targets such as <6.5% (HbA1C≤48mmol/mol) may be proper for spesific individuals if this can be attained without adverse effects of treatment or significant hypoglycemia. This more stringent target applies to those who have had diabetes for a short time and have better β-cell function and patients treated with metformin or lifestyle only and who attain significant weight progress (American Diabetes Association 2019). The target of fasting glucose is below 7 mmol/l, and below 10 mmol/l after two hours of eating. Low density lipoprotein (LDL) should be below 2.5mmol/l in all people with diabetes and below 1.8mmol/l in people with diabetes and high cardiovascular risk or a cardiovascular event. The recommended blood pressure is below 140/80 mmHg (Diabetes: Finnish Current Care Guidelines, 2020).
To prevent complications in people with diabetes it is important to control risk factors such as hyperglycemia, high blood pressure, smoking, dyslipidemia, and excess weight. Medication and individual support are important, and should take into account the patient´s knowledge, psychological, social and economic
resources (Peeples et al. 2007, Canadian Diabetes Association 2013, American Diabetes Association 2019, diabetes: Finnish Current Care Guidelines 2020).
In The ADA ´s annual major updates of 2019, the focus is on the tailored care of the individual, cardiovascular disease (CVD) in people with diabetes, and diabetes technology for older adults. Moreover, the guidelines now include a section of lifestyle management (American Diabetes Association 2019). There is a target to halt the rise in diabetes and obesity by 2025 globally (World Health Organization 2016).
1.2.5 Diabetes in older people
In older people the incidence of diabetes increases until approximately 65 years, after which both prevalence and incidence appear to stabilize. The prevalence of diabetes in adults over 65 years varies from 22% to 33% (Kirkman et al. 2012). In this group of adults the number of diagnosed diabetes may increase by 4.5-fold in 2005-2050 while the increase is 3-fold in the total population (Narayan et al. 2006).
Because of aging, people are prone to increasing insuline resistance and impaired pancreatic islet function and therefore having type 2 diabetes. In older people, insulin resistance is associated with sarcopenia, adiposity, and physical inactivity (Amati et al. 2009).
The alignment of treatment goals is similar among the ADA, diabetes specialists in Europe and in Finland (American Diabetes Association 2019, Hambling et al.
2019, Diabetes: Finnish Current Care Guidelines 2020).
The minimum goal of treatment is to be asymptomatic (no tiredness, polyuria, thirst, losing weight, delirium or sensitivity to infections). Hypoglycemia should be avoided. In an otherwise healthy person under 75 years of age, the glycemic goals are the same as for younger people. If there is a possibility of hypoglycemia, the goal of HbA1c can be 58-69 mmol/mol. For older persons consideration should be given to comorbidities, function and quality of life. In people 75 or older, glycemic targets are individualized and the most important issues to be considered are having the best possible quality of life and being independent and asymptomatic.
The new five-cluster classification of type 2 diabetes can identify patients who are at high risk of diabetic complications, and moreover gives information about the disease mechanism (Ahlqvist et al 2018).
1.2.6 Comorbidities among older people with diabetes
Compared with people without diabetes, older people with diabetes have an increased prevalence and incidence of pain, polypharmacy, low body mass index, cognitive impairment, falls, dizziness, incontinence, vision and hearing impairment, (Cigolle et al. 2010) (table 2). In addition, older people with diabetes have more premature deaths, functional disability, hypertension, depressive symptoms and coronary heart disease (Forssas et al. 2010, Kamradt et al. 2017, Jing et al. 2018) (table 2). In a Finnish study, people with type 2 diabetes had almost double the mortality rate compared with the control population (Forssas et al. 2010).
In a Finnish study made in northern Finland with older people, there is an association of depressive symptoms between both prediabetes and diabetes
(Perkkiö et al. 2019). Earlier it was found that people with diabetes aged 45-74 had more depressive symptoms than people without diabetes or impaired glucose tolerance (Mäntyselkä et al. 2011). In two longitudinal studies, older people with depressive symptoms had a 1.6-2.5-fold risk of developing diabetes (Carnethon et al 2003, Demakakos et al. 2010, Park et al 2014). Depression increased
substantially (60%) the risk of type 2 diabetes (Mezuk et al. 2008).
All these conditions and comorbidities may affect the self-management of diabetes (Kirkman et al. 2012, World Health Organization 2016, Centers for Disease Control and Prevention 2017). These conditions are associated with lower HRQoL (Yang et al. 2019), and they can worsen their self-management either directly or indirectly. Dementia and advanced heart failure can directly influence diabetes self-management (Piette et al. 2006). Chronic pain and depression can indirectly limit diabetes self-management, decreasing daily activities and regular exercise (Krein et al. 2005).
Table 2. Conditions associated with diabetes in older people
Common conditions among older people with diabetes
Other conditions with diabetes
Pain, polypharmacy, low body mass index, cognitive impairment, falls, dizziness, incontinence, vision impairment, hearing
impairment
Premature deaths, depression, functional disability, hypertension and coronary heart
disease Cigolle et al. 2010, Forssas et al. 2010, Kamradt et al. 2017, Jing et al. 2018.