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DIABETES MELLITUS
A Silent Killer BY MIAN A. JAN, M.D., F.A.C.C., F.S.C.A.I., AND AHMED SHAMSI
Introduction Diabetes mellitus (DM) is a chronic metabolic disease characterized by elevated blood glucose levels (hyperglycemia). DM may result from defects in insulin secretion, resistance to insulin action, or both. Approximately 537 million adults (2079 years) had diabetes in 2021 according to the International Diabetes Federation (IDF), with a projected rise to 643 million adults by 2031. Progression of diabetes mellitus results in tissue and blood vessel damage leading to severe complications including retinopathy, neuropathy, and nephropathy as well as cardiovascular complications. Diabetes mellitus is a silent killer, with approximately 7.3 million U.S. adults who met laboratory criteria for diabetes not being aware of or reporting having diabetes.
Etiology In the pancreas, there are two major classes of hormoneproducing cells: the insulin-secreting beta cells, and the glucagonsecreting alpha cells. Insulin induces muscle and liver cells to take up glucose, decreasing blood glucose concentration, whereas glucagon serves to increase the concentration of blood glucose. Without the balance of insulin and glucagon, glucose levels will reach improper concentrations. In the case of diabetes mellitus, insulin is either absent, or there is receptor level resistance to the effects of insulin, leading to hyperglycemia. The vast majority of diabetes cases fall into two broad categories by etiology: type 1 diabetes, and type 2 diabetes.
Type 1 Diabetes Mellitus (T1DM) Type 1 diabetes mellitus (T1DM) accounts for 5-10% of those with diabetes. T1DM is characterized by the destruction of beta cells in the pancreas, resulting in absent or extremely low insulin production. Markers of the destruction of beta cells include antibodies against islet cells, insulin, glutamic acid decarboxylase-65 (GAD-65), and tyrosine phosphatases IA-2 and IA-2ß. At least one of these autoantibodies is present in 85-90% of individuals when fasting hyperglycemia is initially detected. This form of diabetes most commonly occurs in children and adolescents and is associated with genetic predisposition and environmental factors such as viruses or toxins. 24 CHESTER COUNT Y Medicine | WINTER 2022
Type 2 Diabetes Mellitus (T2DM) Type 2 diabetes mellitus (T2DM) is far more frequent than T1DM, accounting for 90% to 95% of those with diabetes. T2DM is characterized by a diminished response to insulin by muscle, fat, and liver cells, which is termed insulin resistance. Insulin resistance is initially countered by an increased production of insulin by the pancreas to maintain normal blood glucose levels. Over time, however, insulin production decreases and type 2 diabetes mellitus is diagnosed. T2DM is often undiagnosed for many years due to the gradual development of hyperglycemia, and early symptoms that are not severe enough to be recognized by patients. The risk of developing T2DM increases with age, obesity, and physical inactivity, and is associated with a strong genetic predisposition.
