Conventional wisdom is that breath acetone may be markedly elevated in type 1 diabetes, but that this only occurs during poor blood glucose control and/or intercurrent illness. In contrast, little is known about breath acetone at more representative everyday blood glucose levels in diabetes. We used selected ion flow tube mass spectrometry to monitor the breath of eight patients with type 1 diabetes mellitus during 'insulin clamp' studies in which insulin and glucose were infused into patients to lower blood glucose levels in steps from normal values into the low glucose (hypoglycaemic) range. The concentration of acetone in breath and the blood sugar concentration of the patients were monitored at each blood glucose concentration. The blood glucose level at the start of the study was typically about 6 mM L(-1), whereas the breath acetone concentration at this blood glucose level was unexpectedly variable, ranging from 1 part-per-million to 21 ppm, in contrast to what was previously believed, i.e. that type 1 diabetes mellitus is characterized by high acetone levels. In all eight patients, the breath acetone declined linearly with blood glucose concentration.

The pathogenesis and complications of type 2 diabetes (T2DM) are closely linked with defective glucose metabolism, obesity, cardiovascular disease and an inability to mount an effective immune response to certain pathogenic organisms. Perturbations in key innate immune receptors known as Toll-like receptors (TLRs) and inflammatory mediators such as IL-6, TNFα and IL-1β have been linked with T2DM. Herein, we sought to establish whether patients with T2DM and underlying complications exhibit perturbations in cytokine and TLR expression. Serum cytokine and mRNA levels of cytokines/TLRs in monocytes (M) and neutrophils (N) were measured in a cohort of 112 diabetic patients: good glycaemic control without complications (GC), good glycaemic control with complications (GCC), poor glycaemic control without complications (PC) and poor glycaemic control with complications (PCC) and compared them with 34 non-diabetic volunteers (NGT). Serum cytokine levels were normal in all study participants. In the GC group, cytokine and TLR gene expression were enhanced compared to NGT. In contrast, suppressed cytokine and TLR gene expression were evident in PC, GCC & PCC groups when compared to the GC. In conclusion, whereas serum pro-inflammatory cytokine levels are unaltered in T2DM patients, differences in inflammatory gene profiles exist among the T2DM patient groups.

The mechanisms underpinning impaired defensive counterregulatory responses to hypoglycemia that develop in some people with diabetes who suffer recurrent episodes of hypoglycemia are unknown. Previous work examining whether this is a consequence of increased glucose delivery to the hypothalamus, postulated to be the major hypoglycemia-sensing region, has been inconclusive. Here, we hypothesized instead that increased hypothalamic glucose phosphorylation, the first committed intracellular step in glucose metabolism, might develop following exposure to hypoglycemia. We anticipated that this adaptation might tend to preserve glucose flux during hypoglycemia, thus reducing detection of a falling glucose. We first validated a model of recurrent hypoglycemia in chronically catheterized (right jugular vein) rats receiving daily injections of insulin. We confirmed that this model of recurrent insulin-induced hypoglycemia results in impaired counterregulation, with responses of the key counterregulatory hormone, epinephrine, being suppressed significantly and progressively from the first day to the fourth day of insulin-induced hypoglycemia. In another cohort, we investigated the changes in brain glucose phosphorylation activity over 4 days of recurrent insulin-induced hypoglycemia. In keeping with our hypothesis, we found that recurrent hypoglycemia markedly and significantly increased hypothalamic glucose phosphorylation activity in a day-dependent fashion, with day 4 values 2.8 ± 0.6-fold higher than day 1 (P < .05), whereas there was no change in glucose phosphorylation activity in brain stem and frontal cortex. These findings suggest that the hypothalamus may adapt to recurrent hypoglycemia by increasing glucose phosphorylation; and we speculate that this metabolic adaptation may contribute, at least partly, to hypoglycemia-induced counterregulatory failure.