Control of Diabetes Mellitus in Shift Workers

Objective: To determine whether the control of diabetes is different in insulin treated diabetic subjects who work shifts compared with those who do not work shifts and whether control is related to the type of shift worked.

Design: Prospective controlled study of 32 diabetic subjects working either regular days or shifts in a large car assembly factory. Insulin treated subjects who underwent a change in their pattern of shift work had diabetic control assessed before and six months after a change in shifts.

Main Outcome Measures: Random plasma glucose, serum fructosamine, and haemoglobin A1 while at work.

Results: Diabetic control of insulin treated subjects who worked shifts was not significantly different from insulin treated subjects who worked days only. Diabetic control was poor in both groups and similar to that of diabetic subjects treated with oral hypoglycaemic agents. In those subjects that moved to a more rapidly rotating shift pattern there was a significant deterioration in control (serum fructosamine concentration before, 405 (SD 68); after, 481 (SD 90) mumol/l, p less than 0.01).

Conclusions: The control of diabetes in insulin treated diabetic subjects who worked shifts was no worse than those who worked days only. Slowly rotating shifts were associated with better diabetic control than more rapidly rotating shifts.