If you have type 1 diabetes, your body produces little or no insulin, and you survive on injections of synthetic insulin. You always have a little too much or too little insulin running through your blood, except for times when you have a lot too much or too little. Too much, and you may start to slide rather quickly toward serious wooziness and maybe unconsciousness. Too little, and you increase your risk of serious complications down the road.

Thus the appeal of the concept of “smart insulin”, an insulin derivative designed to automatically react to the level of blood glucose and adjust the amount of insulin released so that glucose levels remain in a healthy range.

Back in 1979, Michael Brownlee and Anthony Cerami presented one smart insulin approach in Science. There’s been plenty of research on the concept since then, but it has remained a concept.

In 2010, though, Merck announced plans to buy the MIT spinoff SmartCells for a purchase price that may eventually exceed $500 million. And last week at a Merck investor briefing, Roger Perlmutter, executive vice president and president of Merck Research Laboratories, noted that the company plans to move a smart insulin candidate based on SmartCells work forward into clinical trials.

At the briefing, Perlmutter displayed just one slide, showing that injections of a drug candidate called L-490 could maintain blood glucose levels at normal levels in dogs using smaller dosages than needed with regular synthesized human insulin, thus suggesting that L-490 indeed was releasing insulin only as needed.

Merck’s plan for a trial drew little attention outside the type 1 community, as the markets concentrated on other drugs headed for bigger markets sooner. But if smart insulin works it might radically improve treatment not only for the millions with type 1 diabetes but for the substantial group of people with type 2 diabetes who already use insulin among their other therapies.