Diabetes, glycemic control, and risk of tuberculosis: a population-based case-control study

To examine the association between diabetes, glycemic control, and risk of tuberculosis (TB).

We conducted a population-based case-control study in Northern Denmark. Cases of active TB were all individuals with a first-time principal hospital diagnosis of TB between 1980 and 2008. Each case subject was matched with up to five population control subjects with similar age, sex, place and length of residence in Denmark, and country of emigration. We computed odds ratios (ORs) for a first-time TB diagnosis among people with and without diabetes using regression to control for other comorbidities, alcoholism, immunosuppressive medications, and socioeconomic markers.

We identified 2,950 patients, including 156 diabetic individuals (5.3%), with active TB, and 14,274 population control subjects, of which 539 had diabetes (3.8%). The adjusted OR for active TB among subjects with diabetes was 1.18 (95% CI 0.96-1.45) compared with nondiabetic individuals. We found a similar risk increase from diabetes in the 843 (29%) TB case subjects who were immigrants; adjusted OR = 1.23 (95% CI 0.78-1.93). In a subset with laboratory data, diabetic individuals with an HbA(1c) <7.0, 7-7.9, and ≥8.0% had ORs of 0.91 (0.51-1.63), 1.05 (0.41-2.66), and 1.19 (CI 0.61-2.30), respectively, compared with individuals without diabetes.

In the low TB-burden country of Denmark, the TB risk increase associated with diabetes is substantially lower than previously suggested. We found no evidence for any association between TB and dysglycemia.