Diabetes, junk food and sleep.

I came across the article "Gene connects lack of shut-eye with diabetes" (SN: 1/3/09, p. 5) after having just worked more than 24 hours. While it is no longer common for physicians in an operating room to work 48-72 hours without sleep, 18-36 hours is still not exceptional. What was especially fascinating to me was the finding by James Gangwisch that sleep-deprived people "crave starchy, sweet foods." Ordinarily I am a granola, yogurt, fruits and nuts sort of person. However, on-call and working more than about 18 hours, caffeine completely loses its effect. Nothing but the purest junk food keeps me functional: Oreos, Doritos, chocolate, jelly beans, cookies and other candy are the middle-of-the-night foods of choice. I have long put this eating behavior down to a moral failing on my part, and am relieved to find that it has firm physiologic roots. Knowing this will delay my eating such things as long as possible, but, at some point, the exigencies of providing medical care will force a relapse, for truly, especially as one gets older, consuming vast amounts of sugar is the only way to remain functional.

Gordon M. Verber, San Antonio, Texas

As a diabetic, I was fascinated by the article about diabetes and lack of sleep. But the need for exercise to prevent lack of sleep and the onset of diabetes was ignored. Until I was over 80, I walked at least two miles every day and had no problem sleeping and no diabetes. Then my husband had several strokes and my life revolved around his care. I could no longer get out and walk. After a couple of years, I was diagnosed with diabetes. My sleeping patterns had become erratic, ranging from three to six hours a night. Lately, I have found in-home care for my husband and have been able to get away now and then. It appears to be helping.

Millie Glick, Montesano, Wash.

The article reporting an exciting link between melatonin and type 2 diabetes implied a causal relationship between sleep deprivation and insulin levels suppressed by nighttime melatonin release. This leads to high blood sugar levels and development of type 2 diabetes. A simpler mechanism might be late consumption of a large meal coincident with suppressed insulin levels due to nighttime melatonin release, with the same outcome. While urban Europeans are known for their late dinners and (presumably) disturbed sleep cycles, they do not appear to have the same frequencies of type 2 diabetes. That might relate to much smaller dinner portions--less blood sugar is produced, and insulin levels reduced by melatonin are less critical, and therefore unlikely to lead to type 2 diabetes. Occam's razor would suggest this is quite possible, and it seems more consistent with recent American eating and sleeping habits.

Karl Hoenke, Walnut Creek, Calif.

The article reported on a study showing an association between variants of the melatonin receptor--a protein important for sleep-wake cycles--and the risks of developing type 2 diabetes, but the details are still a mystery. This leaves "room for interpretation, and future experiments, to demonstrate the true causal pathway," says statistical geneticist Goncalo Abecasis of the University of Michigan. The people included in the study, both those with a higher risk of developing diabetes and the control group, presumably are a wide variety of diets. Until more directed studies are conducted, the effects of mealtime and portions on sleep and blood sugar won't be clean.--Laura Sanders