While four studies conclude better implant survival and less peri-implant complications in the well-controlled group, the three others see no difference in implant success even in the poorly controlled patients. The study of Khandelwal treated exclusively patients with poor glycemic control (HbA1c 7.5–11.4 %) and had 98 % implant survival, after 4 months; therefore, he concluded that implant therapy is successful even in poorly controlled diabetes.

Influence of duration of diabetes disease

It is plausible that with extended duration of diabetes, the systemic side effects increase. However, the influence of duration of the disease on implant surgery outcome is only very little examined. Most of the included studies (17 of 22) provided no data about duration since diagnosis of diabetes. In five studies, these data were given, but only two of them analyzed the influence on the implant survival. While Olsen concludes that the duration of diabetes may be associated with implant failure, Tawil says that implant survival is independent from diabetes duration.

Influence of supportive therapy

Although there is some controversy over the use of antibiotics in healthy patients, these are recommended in diabetic patients in implant surgery. The reason is the impaired immune system, which can lead to wound infections and healing complications. Some authors indicate the administration of antibiotics for 5–7 days postoperatively; others support the view that there is no significant reduction of wound infection when using antibiotics more than 1 day after surgery. Our literature search resulted in one prospective study that shows a clear benefit using preoperative antibiotics in both type II diabetics and non-diabetics. For implants in the non-type II diabetic group, survival for those implants placed with preoperative antibiotics was 4.5 % higher than implants not provided coverage at placement surgery. This improvement in survival was even greater (10.5 %) for those in the type II diabetic group. These outcomes are clinically important and should be considered clinically significant. But the authors do not describe which antibiotic they used and how long it was administered.

There was a large improvement in implant survival in the type II diabetic patients when chlorhexidine (CHX) (95.6 %, 4.4 % failures) was used at the time of implant placement, as compared to when CHX was not used (86.5 %, 13.5 % failures). This difference in survival (9.1 %) was large enough to be considered clinically significant but was not found in the non-type II diabetic patient. For the non-diabetic group, survival increased only slightly when CHX was used (94.3 %, 5.7 % failures), compared to when CHX was not used (91.8 %, 8.2 % failures).