An adipocyte-derived peptide, adiponectin (also known as GBP28), is decreased in subjects with type 2 diabetes. Recent genome-wide scans have mapped a diabetes susceptibility locus to chromosome 3q27, where the adiponectin gene (APM1)

Concept of Diabetes Mellitus: Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long-term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder. Classification (Tables 1 and 2, and Figure 1): The classification of glucose metabolism disorders is principally derived from etiology, and includes staging of pathophysiology based on the degree of deficiency of insulin action. These disorders are classified into four groups: (i) type 1 diabetes mellitus; (ii) type 2 diabetes mellitus; (iii) diabetes mellitus due to other specific mechanisms or diseases; and (iv) gestational diabetes mellitus. Type 1 diabetes is characterized by destruction of pancreatic b-cells. Type 2 diabetes is characterized by combinations of decreased insulin secretion and decreased insulin sensitivity (insulin resistance). Glucose metabolism disorders in category (iii) are divided into two subgroups; subgroup A is diabetes in which a genetic abnormality has been identified, and subgroup B is diabetes associated with other pathologic disorders or clinical conditions. The staging of glucose metabolism includes normal, borderline and diabetic stages depending on the degree of hyperglycemia occurring as a result of the lack of insulin action or clinical condition. The diabetic stage is then subdivided into three substages: non-insulin-requiring, insulin-requiring for glycemic control, and insulin-dependent for survival. The two former conditions are called non-insulin-dependent diabetes and the latter is known as insulin-dependent diabetes. In each individual, these stages may vary according to the deterioration or the improvement of the metabolic state, either spontaneously or by treatment. Diagnosis (Tables 3-7 and Figure 2): Categories of the State of Glycemia: Confirmation of chronic hyperglycemia is essential for the diagnosis of diabetes mellitus. When plasma glucose levels are used to determine the categories of glycemia, patients are classified as having a diabetic type if they meet one of the following criteria: (i) fasting plasma glucose level of ‡126 mg/dL ( ‡7.0 mmol/L); (ii) 2-h value of ‡200 mg/dL ( ‡11.1 mmol/L) in 75 g oral glucose tolerance test (OGTT); or (iii) casual plasma glucose level of ‡200 mg/dL ( ‡11.1 mmol/L). Normal type is defined as fasting plasma glucose level of <110 mg/dL (<6.1 mmol/L) and 2-h value of <140 mg/dL (<7.8 mmol/L) in OGTT. Borderline type (neither diabetic nor normal type) is defined as falling between the diabetic and normal values. According to the current revision, in addition to the earlier listed plasma glucose values, hemoglobin A 1c (HbA 1c ) has been given a more p...

Concept of Diabetes Mellitus:Diabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long‐term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder.Classification (Tables 1 and 2, and Figure 1):Table 1 Etiological classification of diabetes mellitus and glucose metabolism disordersI. Type 1 (destruction of pancreatic β‐cells, usually leading to absolute insulin deficiency) A. Autoimmune B. IdiopathicII. Type 2 (ranging from predominantly insulin secretory defect, to predominantly insulin resistance with varying degrees of insulin secretory defect)III. Due to other specific mechanisms or diseases (see Table 2 for details) A. Those in which specific mutations have been identified as a cause  of genetic susceptibility  (1) Genetic abnormalities of pancreatic β‐cell function  (2) Genetic abnormalities of insulin action B. Those associated with other diseases or conditions  (1) Diseases of exocrine pancreas  (2) Endocrine diseases  (3) Liver disease  (4) Drug‐ or chemical‐induced  (5) Infections  (6) Rare forms of immune‐mediated diabetes  (7) Various genetic syndromes often associated with diabetesIV. Gestational diabetes mellitusNote: Those that cannot at present be classified as any of the above are called unclassifiable.The occurrence of diabetes‐specific complications has not been confirmed in some of these conditions.Table 2 Diabetes mellitus and glucose metabolism disorders due to other specific mechanisms and diseasesA. Those in which specific mutations have been identified as a cause of genetic susceptibilityB. Those associated with other diseases or conditions(1) Genetic abnormalities of pancreatic β‐cell function
Insulin gene (abnormal insulinemia, abnormal proinsulinemia, neonatal diabetes mellitus) 
HNF 4α gene (MODY1) 
Glucokinase gene (MODY2) 
HNF 1α gene (MODY3) 
IPF‐1 gene (MODY4) 
HNF 1β gene (MODY5) 
Mitochondria DNA (MIDD) 
NeuroD1 gene (MODY6) 
Kir6.2 gene (neonatal diabetes mellitus) 
SUR1 gene (neonatal diabetes mellitus) 
Amylin
Others
(2) Genetic abnormalities of insulin action
Insulin receptor gene (type A insulin resistance, leprechaunism, Rabson–Mendenhall syndrome etc.) 
Others(1) Diseases of exocrine pancreas
Pancreatitis
Trauma/pancreatectomy
Neoplasm
Hemochromatosis
Others
(2) Endocrine diseases
Cushing’s syndrome
Acromegaly
Pheochromocytoma
Glucagonoma
Aldosteronism
Hyperthyroidism
Somatostatinoma
Others
(3) Liver disease
Chronic hepatitis
Liver cirrhosis 
Others
(4) Drug‐ or chemical‐induced
Glucocorticoids
Interferon
Others
(5) Infections
Congenital rubella
Cytomegalovirus
Others
(6) Rare forms of immune‐mediated diabetes
Anti‐insulin receptor antibodies
St...

Summary Concept of diabetes mellitusDiabetes mellitus is a group of diseases associated with various metabolic disorders, the main feature of which is chronic hyperglycemia due to insufficient insulin action. Its pathogenesis involves both genetic and environmental factors. The long-term persistence of metabolic disorders can cause susceptibility to specific complications and also foster arteriosclerosis. Diabetes mellitus is associated with a broad range of clinical presentations, from being asymptomatic to ketoacidosis or coma, depending on the degree of metabolic disorder.Classification (Tables 1, 2; Fig. 1) The classification of glucose metabolism disorders is principally derived from etiology, and includes staging of pathophysiology based on the degree of deficiency of insulin action. These disorders are classified into four groups: (i) type 1 diabetes mellitus; (ii) type 2 diabetes mellitus; (iii) diabetes mellitus those due to other specific mechanisms or diseases; and (iv) gestational diabetes mellitus. Type 1 diabetes is characterized by destruction of pancreatic b-cells. Type 2 diabetes is characterized by combinations of decreased insulin secretion and decreased insulin sensitivity (insulin resistance). Glucose metabolism disorders in category (iii) are divided into two subgroups; subgroup A is diabetes in which a genetic abnormality has been identified, and subgroup B is diabetes associated with other pathologic disorders or clinical conditions.

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