Epidemiology of diabetes mellitus

Abstract

Diabetes mellitus is increasingly being recognised as a disorder of insulin secretion inadequate or inappropriate for a given blood sugar state. Easily identified disorders of insulin secretion may precede by many years the breakdown in carbohydrate tolerance. The accurate definition and diagnosis of diabetes mellitus can lead to controversy but WHO standards are advised. All good statistical evidence currently available points to the fact that blood sugars of between 130 and 200 mg/100 ml as well as any figure above 200 mg, 2 hr or more after 50 g of glucose, are diabetogenic. Blood sugar levels of over 200 mg lead to premature atheroma. All evidence available on careful studies indicates that blood sugar levels between 130 and 200 mg are also probably atherogenic. Frank diabetes mellitus leads to an increased mortality from vascular disease in patients compared with well matched control groups. The disorder also leads to specific diabetic angiopathy or small vessel disease, 50% of diabetics showing some evidence of retinopathy after 15 yr duration of the condition. Personal studies from 93% of the adult population of a New Zealand town indicate that just on 4% of the population have diabetes mellitus by present criteria. The prevalence is between 10 and 15% in adult polynesian people in New Zealand. Those with blood sugars between 110 and 129 mg 2 hr after the glucose load were studied 4 yr later. One third of them had mild carbohydrate intolerance and one third had abnormal insulin secretion patterns. As polynesian rates for diabetes are double those of pakehas (white population) and because available evidence suggests an increasing prevalence in the future, careful studies on the epidemiological factors possibly associated with diabetes mellitus are indicated in the disease so ubiquitous in its occurrence, so common in its presentation, and so devastating in its effects.