Type 2 diabetes mellitus

Introduction
This is a group of disorders characterized by hyperglycemia and associated with microvascular, macrovascular complications. Unlike type 1 diabetes mellitus, the patients are not absolutely dependent upon insulin for life, even though many of these patients ultimately are treated with insulin.
How does it happen (Pathophysiology)?
Muscles, fat and liver are the major sites where insulin acts. But in type 2 DM these sites offer a resistance to insulin therefore metabolism of carbohydrates, fat and protein become abnormal. This pathophysiologic abnormality results in decreased glucose transport in muscle, elevated hepatic glucose production, and increased breakdown of fat. Therefore hyperglycemia will result.
The genetic aspects of this condition is very complex and not completely understood, but presumably this disease is related to multiple genes (with the exception of maturity-onset diabetes of the young [MODY]). Evidence supports inherited components for both pancreatic beta cell failure and insulin resistance.
Recent work has suggested that elevated free fatty acids may be the driving force behind insulin resistance and perhaps even beta cell dysfunction. If this defect is more proximal than defects specifically related to glycemia, then therapies aimed at correcting this phenomenon would be highly beneficial.
Hyperglycemia appears to be the determinant of microvascular and metabolic complications. However, glycemia is much less related to macrovascular disease. Insulin resistance with concomitant lipid (ie, small dense low-density lipoprotein [LDL] particles, low high-density lipoprotein-cholesterol [HDL-C] levels, elevated triglyceride-rich remnant lipoproteins) and thrombotic (ie, elevated type-1 plasminogen activator inhibitor [PAI-1], elevated fibrinogen) abnormalities, as well as conventional atherosclerotic risk factors (eg, family history, smoking, hypertension, elevated low-density lipoprotein-cholesterol [LDL-C], low HDL-C), determine cardiovascular risk.
Epidemiology
Type 2 diabetes mellitus is less common in non-Western countries where the diet contains fewer calories and caloric expenditure on a daily basis is higher. However, as people in these countries adopt Western lifestyles, weight gain and type 2 diabetes mellitus are becoming virtually epidemic.
The prevalence of type 2 diabetes mellitus varies widely among various racial and ethnic groups Type 2 diabetes mellitus is becoming virtually pandemic in some groups of Native Americans and Hispanic people. Recent work suggests more retinopathy and nephropathy in blacks, Native Americans, and Hispanic groups.
Type 2 diabetes mellitus is slightly more common in older women than men.
While type 2 diabetes mellitus traditionally has been thought to affect individuals older than 40 years, it is being recognized increasingly in younger persons, particularly in highly susceptible racial and ethnic groups.

Type 2 diabetes mellitus is slightly more common in older women than men.
Diabetes mellitus is one of the leading causes of morbidity and mortality because of its role in the development of optic, renal, neuropathic, and cardiovascular disease. These complications, particularly cardiovascular disease (~50-75% of medical expenditures), are the major sources of expenses for patients with diabetes mellitus.