Implants in diabetes: HbA1c below 7% is the threshold, not the diagnosis

Clinical question: Can patients with diabetes mellitus receive dental implants with confidence, or does the disease undermine the result? This systematic review weighed survival, peri-implant health, the role of glycemic control and the value of adjunctive therapies.

Methodology: Following PRISMA 2020, the authors searched multiple databases through July 2025 and included both clinical studies in diabetic patients and relevant animal models. Methodological quality was assessed with the appropriate tool for each design — CONSORT for trials, STROBE for observational work, ARRIVE for preclinical studies. From 3,637 records, 54 studies were retained.

Main findings: The headline is nuanced. Overall implant survival in diabetic patients was often high, above 90-95%. But the average conceals a threshold. Diabetes — especially when poorly controlled, with HbA1c above 8% — was consistently linked to worse outcomes: greater marginal bone loss, deeper probing depths, more bleeding on probing, and higher peri-implant inflammatory markers such as IL-6 and TNF-α. Crucially, well-controlled diabetics (HbA1c ≤ 7%) often performed on par with non-diabetic patients. Two adjunctive strategies stood out. Antimicrobial photodynamic therapy (aPDT) improved clinical parameters and reduced inflammation. And preclinical work on bioactive coatings and 3D-printed porous implant surfaces showed enhanced osseointegration under diabetic conditions.

Clinical relevance: Diabetes is not a contraindication to implant therapy — poor glycemic control is the real risk factor. The distinction matters at the chair. Before placing implants in a diabetic patient, the number to ask for is the HbA1c, not merely the diagnosis. A patient at or below 7% can be treated with expectations close to those of a healthy patient; above 8%, the clinician should anticipate more inflammation, more bone loss and a higher chance of failure, and plan accordingly: tighter case selection, coordination with the patient's physician to improve control, meticulous maintenance and a lower threshold for adjuncts like aPDT. The preclinical surface data point to where the field is heading, but they are not yet clinical recommendations. The practical takeaway is disciplined and reassuring: control the metabolism first, then the implant follows.