Table 1 List of the included studies and its main characteristics

Author	Year	Study type	Diabetes type	Control	Diabetes therapy	Glycemic control [HbA1c %]	Duration of diabetes (years)	Number of patients	Number of implants	Duration of study (years)	Implant survival [%]	Conclusion
Alsaadi	2007	Retrospective	Type II	Non-diabetes	n.d.	n.d.	n.d.	2004 (overall)	6946 (overall)	6 months	96.4 (global)	Diabetes does not cause higher failure rate in the first 6 months.
Aguilar-Salvatierra	2015	Prospective	Type II	3 groups (HbA1c)	n.d.	6–8 (well), 8–10 (moderately), >10 (poorly)	n.d.	85	85	2	100 vs. 96.6 vs. 86.3	Patients with diabetes can receive implant-based treatments, providing they present moderate HbA1c values. Peri-implantitis increases with elevated HbA1c.
Anner	2010	Retrospective	n.d.	Non-diabetes	n.d.	n.d.	n.d.	49 diabetes, 475 overall	1626	3 ± 2	97.2 vs. 95	Diabetes was not related to implant survival in this patient cohort.
Busenlechner	2014	Retrospective	n.d.	Non-diabetes	n.d.	n.d.	n.d.	4316	>10,000	8 years	95.1 vs. 97	Diabetes does not have any influence on implant survival after 8 years, if blood sugar is effectively controlled.
Daubert	2015	Cross-sectional	n.d.	Non-diabetes	n.d.	n.d.	n.d.	8 diabetes, 96 overall	225	10	n.d.	Significant associations between implant failure and diabetes (relative risk 4.8 and 3.3) and peri-implant diseases and diabetes (relative risk 4.1).
Dowell	2007	Prospective	Type II	Non-diabetes	Diet, oral, insulin and combination	6–8 (well), 8–10 (moderately), >10 (poorly)	n.d.	25 diabetes, 10 non-diabetes	38 diabetes, 12 non-diabetes	4 months	100	Diabetes has no negative influence; the quality of glycemic control has no effect on implant success.
Erdogan	2014	Prospective	Type II	Non-diabetes	n.d.	Mean 6.8	7.5	12 diabetes, 12 control	43	1	100	No significant difference for wound healing, radiographic findings, implant success and volume of augmentation (guided bone regeneration with bone scrapes and bone substitute material).
Ferreira	2006	Cross-sectional	n.d.	Non-diabetes	n.d.	Blood sugar >126 mg/dl or diabetic medication subscribed	n.d.	212 (overall)	578 (overall)	6 months–5 years	n.d.	Risk for peri-implantitis in “uncontrolled” diabetes is 1.9 times higher compared to the non-diabetes group.
Fiorellini	2000	Retrospective	Types I and II	None	n.d.	“Proper levels of glycemic control”	8.9 ± 14.3	40	215	6.5	85.6	Survival rate is lower than for general population, but there is still a reasonable success rate. Most implant failures are in the first year after loading.
Ghiraldini	2015	Prospective	Type II	Non-diabetes	n.d.	<8 (better) >8 (poorly)	10.7 ± 5	16 better, 16 poorly, 19 control	51	1	100	Poor glycemic control negatively modulated the bone factors during healing, although diabetes (regardless of glycemic control) had no effect on implant stabilization.
Gomez-Moreno	2014	Prospective	Type II	4 groups (HbA1c)	n.d.	<6 (healthy), 6–8 (well), 8–10 (moderately) >10 (poorly)	n.d.	67	67	3	n.d.	Elevated HbA1c causes more bone loss (not significant) and significantly higher BOP. Probing depth is not influenced by glycemic control.
Khandelwal	2011	Prospective	Type II	2 different types of implants	n.d.	7.5–11.4 (poorly controlled)	n.d.	24	48	4 months	98	Successful implant therapy in patients suffering poorly controlled diabetes. No difference between the two implant systems.
Morris	2005	Prospective	Type II	Non-diabetes	n.d.	n.d.	n.d.	663	255 diabetes, 2632 non-diabetes	3	92.2 and 93.2, respectively	Diabetic patients tend to have more failures than non-diabetic patients. The use of CHX resulted in a slight improvement in survival in non-diabetic patients and in a greater improvement in type II patients, the same effect for antibiotic use.
Moy	2005	Retrospective	n.d.	Non-diabetes	n.d.	n.d.	n.d.	48 diabetes, 1140 overall	4684 (overall)	up to 20	n.d.	Significantly increased relative risk for implant failure (relative risk = 2.75).
Oates	2009	Prospective	Type II	Non-diabetes	Diet, oral, insulin and combination	6–8 (well), 8–10 (moderately), >10 (poorly)	n.d.	32	42	4 months		Patients with poorly controlled HbA1c have lower stability in the first 2–6 weeks, but it reaches the baseline in the following weeks. But reaching the baseline takes two times the duration it needs in the non-diabetic group.
Oates	2014	Prospective	Type II	Non-diabetes	n.d.	6–8 (well), >8 (poorly)	n.d.	44 well, 19 poorly, 49 control	220	1	99	The initial implant stability is lower in diabetic patient, but 1 year after insertion there in so difference even in the poorly controlled group. Diabetes has no influence on implant survival.
Olson	2000	Prospective, multicenter	Type II	None	Diet, oral, insulin and combination	n.d.	n.d.	89	178	5	91 vs. 88	Implants in mandibular symphysis in diabetic patient are a predictable procedure. Duration of diabetes may be associated with implant failure, CHX improves implant survival.
Peled	2003	Retrospective	Type II	None	n.d.	“Well-controlled,” no data for HbA1c	n.d.	41	141	1 and 5	97.3 vs. 94.4	No correlation was found between failed implants and glucose level. The clinical outcome of dental implants in a selected group of patients with well-controlled type II diabetes mellitus is satisfying and encouraging.
Tawil	2008	Prospective	Type II	Non-diabetes	n.d.	<7 (well), 7–9 (moderately), >9 (poorly) mean 7.2	n.d.	54 diabetes, 54 control	255 diabetes, 244 control	1 to 12	97.2 vs. 98.8	No significant difference for implant survival between the groups and no difference between good and medium glycemic control for bone resorption. Augmentations caused no complications. Duration of diabetes was no confounder.
Tatarakis	2013	Prospective	Type II	None	n.d.	Mean 7.1	n.d.	32	>32	1	n.d.	The clinical, microbiological, salivary biomarkers and psychosocial profiles of patient with diabetes under good control are very similar to those of non-diabetes.
Turkyilmaz	2010	Retrospective	Type II	None	Diet, oral, insulin and combination	5–10	5–21	10	23	1	100	No evidence of diminished clinical success, BOP negative, no pathological probing depth, marginal bone loss 0.3 ± 0.2 mm.
Zupnik	2011	Retrospective	n.d.	Non-diabetes	n.d.	n.d.	n.d.	n.d.	25 diabetes, 316 non-diabetes	4	96.4 (global)	Implant failure (explantation) is 2.57 times higher for patient with diabetes than patients without diabetes after 4 years.

Table 1 List of the included studies and its main characteristics

Table 1 List of the included studies and its main characteristics

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