Insulin Patterns in Equivocal Glucose Tolerance Tests (Chemical Diabetes)

Abstract

Hyperinsulinemic patterns are a well recognized feature of equivocal glucose tolerances of the chemical diabetes type, i.e. those that are neither definitely nondiabetic nor clearly diabetic. A more complete characterization of such insulin responses is obtained when the data are expressed in terms of increments in insulin from the zero time point.Thus, two patterns of insulin increments after oral glucose become evident when the equivocal zone of glucose tolerance is divided into lower and upper segments. Tests in the lower segment show normal increments at the halfhour point of the test; at one hour these tests show excessive increments which persist throughout the five hours of observation. On the other hand, tests in the upper zone show delays in the serum insulin rise at the half-hour point, followed by normal increments at one hour and excessive increments thereafter. The pattern is the same whether or not obesity is present. It is suggested that tests in the equivocal zone of Glucose Tolerance Sum values be taken to be indicative of chemical diabetes. Tests with the Sum in the lower half of the equivocal zone could then represent chemical diabetes with mild intolerance stemming from insulin ineffectiveness, since insulin increments in this group are at or above the mean values recorded in nondiabetic controls. On the other hand, chemical diabetes with moderate glucose intolerance and Glucose Tolerance Sums in the upper half of the equivocal zone would be understood to result from a combination of an initial delay in the serum insulin rise followed by normal and then excessive increments in serum insulin with the latter two indicative of insulin ineffectiveness. However, insulin ineffectiveness may also be present at the time of the insulin delay.High glucose:insulin ratios in tests indicative of chemical diabetes are almost always attributable to higher glucose increments with insulin increments normal or excessive compared to normal glucose tolerances. Deficient insulin increments contribute to the high ratios only at the half-hour point in tests with Glucose Tolerance Sums in the upper zone of equivocal glucose tolerances. DIABETES 22:808-12, November, 1973.

Detection of Diabetes MellitusIn Situ(Occult Diabetes)

“…(146lbs). 5 Twenty-nine percent of males and 40% of females were obese by these criteria (Table III). Increased incidence of obesity was noted in females at the 3point range on the Wilkerson scale.…”

Demonstration of insulin resistance in untreated adult onset diabetic subjects with fasting hyperglycemia.

“…However, at least one extremely important distinction exists between patients with chemical diabetes and those with significant fasting hyperglycemia, and this relates to their insulin response to a glucose challenge. Thus, the insulin response of patients with chemical diabetes is equal to or greater than normal (9)(10)(11)(12)(13). In these patients it seems reasonable to suggest that hyperglycemia is secondary to insulin resistance, and the exaggerated insulin response can be viewed as a compensatory mechanism aimed at minimizing glucose intolerance.…”

Growth Hormone Levels in Chemical Diabetes

“…The intervening GTS 0–2 hr values, between 501 and 800, occupy the equivocal zone, so called because such results can be classified as belonging to either the non‐diabetic or the diabetic type according to the four sets of standards, and hence may be taken to represent chemical diabetes. It is further useful to subdivide this equivocal zone of chemical diabetes into lower and upper segments of GTS 0–2 hr values‐501–650 and 651–800‐because they differ in terms of associated insulinemia (9) and because values in the upper zone consistently indicate diabetes by the criteria of the BDA and F and C (7, 8).…”

“…Although chemical diabetes is found more frequently as age advances, and in our experience affects at least one‐third of patients in and beyond the fifth age decade, it remains an incompletely defined entity (1–4). Equivocal results with the oral glucose tolerance test — not clearly of the non‐diabetic type nor definitely of the diabetic type by several sets of criteria: World Health Organization (5), United States Public Health Service (6), British Diabetic Association (7), and Fajans and Conn (8)—may be taken to indicate chemical diabetes (9). We have described the insulin patterns which characterize such equivocal tolerances in earlier and later age decades (9).…”